adds .editorconfig from mofo-style

.editorconfig

@@ -0,0 +1,10 @@
+# EditorConfig : http://EditorConfig.org - Copied from node_modules/mofo-style
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true

CONTRIBUTING.md

@@ -11,6 +11,10 @@ Refer to the [README](README.md).
 
 ## Code Style
 
+### Editor
+Please use an editor with support for [ESLint](http://eslint.org/) and [EditorConfig](http://editorconfig.org/). Configuration
+files for both tools are provided in the root directory of the project.
+
 ### JavaScript
 
 See [Mozilla Foundation JavaScript Style Guide](https://www.npmjs.com/package/mofo-style)
@@ -55,4 +59,4 @@ Run tests with `mocha` or `npm test`.
     - If your PR is ready for review, another contributor will be assigned to review your PR within 1 business day
     - The reviewer will comment on the PR with a final r+ or r-, along with inline comments on the code (if any)
         - r-: address the comments left by the reviewer. Once you're ready to continue the review, ping the reviewer in a comment.
-        - r+: You code will be merged to `master`
+        - r+: You code will be merged to `master`