Added contributing file to describe how to help out

Author: hannesvdvreken

CONTRIBUTING.md

@@ -0,0 +1,27 @@
+# Contributing
+
+Contributions are **welcome** and will be fully **credited**.
+
+We accept contributions via Pull Requests on [Github](https://github.com/aloha/laravel-twilio).
+
+## Pull Requests
+
+- **[PSR-2 Coding Standard](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md)** - The easiest way to apply the conventions is to run `composer cs`.
+
+- **Add tests!** - Your patch won't be accepted if it doesn't have tests. First write a failing test that describes the bug, then write a fix.
+
+- **Document any change in behaviour** - Make sure the `README.md` and any other relevant documentation are kept up-to-date.
+
+- **Keep it Backwards Compatible** - We try to follow [semver v2.0.0](http://semver.org/). Randomly breaking public APIs is not a good idea.
+
+- **One pull request per feature** - If you want to do more than one thing, send multiple pull requests.
+
+- **Send coherent history** - Make sure each individual commit in your pull request is meaningful.
+
+## Running Tests
+
+``` bash
+$ composer test
+```
+
+**Happy coding**!

composer.json

@@ -27,5 +27,9 @@
             "Aloha\\Twilio\\": "src/"
         }
     },
+    "scripts": {
+        "test": "echo 'No tests yet, please help us out!'",
+        "cs": "php-cs-fixer fix src/ --level=psr2"
+    },
     "minimum-stability": "stable"
 }