Detailed testing instructions. Fixes #53

CONTRIBUTING.md

@@ -0,0 +1,32 @@
+_[How to report a bug](http://polite.technology/reportabug.html)_
+
+## Contributing
+
+To test the Mapbox JavaScript SDK, you'll need all of the dependencies for
+development (git, npm, node), and a valid Mapbox access token that has
+access to all tested services.
+
+Clone this repository
+
+```sh
+$ git clone https://github.com/mapbox/mapbox-sdk-js.git
+$ cd mapbox-sdk-js
+```
+
+Install dependencies
+
+```sh
+$ npm install
+```
+
+Set the access token in your environment
+
+```sh
+$ export MapboxAccessToken=YOUR_ACCESS_TOKEN_HERE
+```
+
+Run the tests
+
+```sh
+$ npm test
+```