migrated from jshint to eslint for more consistency in coding styles.

modified JS files so they pass extensive eslint tests
updated package.json and Gruntfile.js for hinting locally
    using `grunt hint` and on build with travis-ci for each commit.
The travis run should fail if there are eslint errors.

.eslintrc

@@ -0,0 +1,250 @@
+/* https://github.com/eslint/eslint/tree/master/docs/rules */
+{
+    "rules": {
+
+        /*
+            Possible Errors
+            The follow rules point out areas where you
+            might have made mistakes.
+        */
+        "comma-dangle": [2, "never"],
+        "no-cond-assign": 2,
+        "no-console": 2,
+        "no-constant-condition": 2,
+        "no-control-regex": 2,
+        "no-debugger": 1,
+        "no-dupe-args": 2,
+        "no-dupe-keys": 2,
+        "no-duplicate-case": 2,
+        "no-empty-character-class": 2,
+        "no-empty": 2,
+        "no-ex-assign": 2,
+        "no-extra-boolean-cast": 2,
+        "no-extra-semi": 2,
+        "no-func-assign": 2,
+        "no-inner-declarations": 2,
+        "no-invalid-regexp": 2,
+        "no-irregular-whitespace": 2,
+        "no-negated-in-lhs": 2,
+        "no-obj-calls": 2,
+        "no-regex-spaces": 2,
+        "no-sparse-arrays": 2,
+        "no-unexpected-multiline": 2,
+        "no-unreachable": 2,
+        "use-isnan": 2,
+        "valid-jsdoc": 2,
+        "valid-typeof": 2,
+
+        // ignored possible errors
+        "no-extra-parens": 0,
+
+
+        /*
+            Best Practices
+            These are rules designed to prevent you from making
+            mistakes. They either prescribe a better way of
+            doing something or help you avoid footguns.
+        */
+        "accessor-pairs": [2, {
+            "getWithoutSet": true
+        }],
+        "block-scoped-var": 2,
+        "complexity": [2, 20], /** TODO should try to get this lower **/
+        "consistent-return": 2,
+        "curly": 2,
+        "default-case": 2,
+        "dot-location": [2, "property"],
+        "dot-notation": 2,
+        "eqeqeq": 2,
+        "guard-for-in": 2,
+        "no-alert": 2,
+        "no-caller": 2,
+        "no-div-regex": 2,
+        "no-empty-label": 2,
+        "no-empty-pattern": 2,
+        "no-eq-null": 2,
+        "no-eval": 2,
+        "no-extend-native": 2,
+        "no-extra-bind": 2,
+        "no-fallthrough": 2,
+        "no-floating-decimal": 2,
+        "no-implicit-coercion": 2,
+        "no-implied-eval": 2,
+        "no-iterator": 2,
+        "no-labels": 2,
+        "no-lone-blocks": 2,
+        "no-loop-func": 2,
+        "no-multi-spaces": 2,
+        "no-multi-str": 2,
+        "no-native-reassign": 2,
+        "no-new-func": 2,
+        "no-new-wrappers": 2,
+        "no-new": 2,
+        "no-octal-escape": 2,
+        "no-octal": 2,
+        "no-process-env": 2,
+        "no-proto": 2,
+        "no-redeclare": 2,
+        "no-return-assign": 2,
+        "no-script-url": 2,
+        "no-self-compare": 2,
+        "no-sequences": 2,
+        "no-throw-literal": 2,
+        "no-unused-expressions": 2,
+        "no-useless-call": 2,
+        "no-useless-concat": 2,
+        "no-void": 2,
+        "no-with": 2,
+        "radix": 2,
+        "wrap-iife": [2, "inside"],
+        "yoda": 2,
+
+        // ignored best practices rules
+        "no-else-return": 0,
+        "no-invalid-this": 0,
+        "no-magic-numbers": 0,
+        "no-param-reassign": 0,
+        "no-warning-comments": 0,
+        "vars-on-top": 0,
+
+
+        /*
+            Strict Mode
+        */
+            "strict": 2,
+
+
+        /*
+            Variables
+            These rules have to do with variable declarations.
+        */
+        "no-catch-shadow": 2,
+        "no-delete-var": 2,
+        "no-label-var": 2,
+        "no-shadow-restricted-names": 2,
+        "no-shadow": 2,
+        "no-undef-init": 2,
+        "no-undef": 2,
+        "no-unused-vars": 2,
+        "no-use-before-define": 2,
+
+        // ignore variable rules
+        "init-declarations": 0,
+        "no-undefined": 0,
+
+
+        /*
+            Stylistic Issues
+            These rules are purely matters of style and
+            are quite subjective.
+        */
+        "array-bracket-spacing": [2, "never"],
+        "block-spacing": [2, "always"],
+        "brace-style": [2, "1tbs", {
+            "allowSingleLine": false
+        }],
+        "camelcase": 2,
+        "comma-spacing": [2, {
+            "before": false,
+            "after": true
+        }],
+        "comma-style": 2,
+        "computed-property-spacing": [2, "never"],
+        "consistent-this": [2, "self"],
+        "constructor-super": 2,
+        "func-style": [2, "declaration"],
+        "id-match": [2, "^[a-z]+([A-Z][a-z]+)*$", {"properties": true}],
+        "indent": [2, 4],
+        "key-spacing": [2, {
+            "beforeColon": false,
+            "afterColon": true,
+            "mode": "strict"
+        }],
+        "max-nested-callbacks": [2, 4],
+        "new-cap": 2,
+        "new-parens": 2,
+        "no-array-constructor": 2,
+        "no-continue": 2,
+        "no-lonely-if": 2,
+        "no-mixed-spaces-and-tabs": 2,
+        "no-multiple-empty-lines": 2,
+        "object-curly-spacing": [2, "never"],
+        "operator-assignment": 2,
+        "operator-linebreak": 2,
+        "quotes": [2, "single"],
+        "semi-spacing": [2, {
+            "before": false,
+            "after": true
+        }],
+        "semi": [2, "always"],
+        "space-after-keywords": [2, "always"],
+        "space-before-blocks": [2, "always"],
+        "space-before-function-paren": [2, "always"],
+        "space-before-keywords": [2, "always"],
+        "space-in-parens": [2, "never"],
+        "space-infix-ops": 2,
+        "space-return-throw-case": 2,
+        "wrap-regex": 2,
+
+        // ignored stylistic rules
+        "eol-last": 0,
+        "func-names": 0,
+        "id-match": 0,
+        "jsx-quotes": 0,
+        "lines-around-comment": 0,
+        "linebreak-style": 0,
+        "newline-after-var": 0,
+        "no-inline-comments": 0,
+        "no-negated-condition": 0,
+        "no-underscore-dangle": 0,
+        "one-var": 0,
+        "padded-blocks": 0,
+        "quote-props": 0,
+        "require-jsdoc": 0,
+        "space-unary-ops": 0,
+        "spaced-comment": 0,
+
+
+        /*
+            ECMAScript 6
+            These rules are only relevant to ES6 environments.
+        */
+        "arrow-parens": [2, "always"],
+        "arrow-spacing": [2, {
+            "before": true,
+            "after": true
+        }],
+        "constructor-super": 2,
+        "generator-star-spacing": [2, {
+            "before": true,
+            "after": true
+        }],
+        "no-class-assign": 2,
+        "no-const-assign": 2,
+        "no-dupe-class-members": 2,
+        "no-this-before-super": 2,
+        "prefer-const": 2,
+        "prefer-spread": 2,
+        "require-yield": 2,
+
+        // ignored ECMA6  rules
+        "no-arrow-condition": 0,
+        "no-var": 0,
+        "object-shorthand": 0,
+        "prefer-arrow-callback": 0,
+        "prefer-reflect": 0,
+        "prefer-template": 0
+
+    },
+    "env": {
+        "amd": true,
+        "es6": true,
+        "browser": true
+    },
+    "globals": {
+        "define": false,
+        "require": false
+    },
+    "parser": "babel-eslint",
+    "extends": "eslint:recommended"
+}