New rule: Disallow string concatenation when using __dirname and __filename (no-path-concat)

Fixes #403

http://eslint.org/docs/2.0.0/rules/no-path-concat

Author: feross

eslintrc.json

@@ -90,6 +90,7 @@
     "no-obj-calls": 2,
     "no-octal": 2,
     "no-octal-escape": 2,
+    "no-path-concat": 2,
     "no-proto": 2,
     "no-redeclare": 2,
     "no-regex-spaces": 2,