fix(gulp): switch to libsass

Ruby sass is not working like this.

Author: stevemao

templates/common/root/_gulpfile.js

@@ -48,8 +48,8 @@ var lintScripts = lazypipe()<% if (coffee) { %>
   .pipe($.jshint.reporter, 'jshint-stylish');<% } %>
 
 var styles = lazypipe()<% if (sass) { %>
-  .pipe($.rubySass, {
-    style: 'expanded',
+  .pipe($.sass, {
+    outputStyle: 'expanded',
     precision: 10
   })<% } %>
   .pipe($.autoprefixer, 'last 1 version')

templates/common/root/_package.json

@@ -25,7 +25,7 @@
     "lazypipe": "^0.2.4",
     "gulp-ng-annotate": "^1.0.0",
     "open": "0.0.5"<% if (sass) { %>,
-    "gulp-ruby-sass": "^0.4.3"<% } %><% if (coffee) { %>,
+    "gulp-sass": "^2.0.4"<% } %><% if (coffee) { %>,
     "gulp-coffeelint": "^0.5.0",
     "gulp-coffee": "^2.3.1",<% } %><% } else { %>
     "autoprefixer-core": "^5.2.1",