Added CONTRIBUTING.md & update Contribute section from Readme

Author: vimishor

CONTRIBUTING.md

@@ -0,0 +1,37 @@
+# Contributing
+
+First of all, thank you for taking time to contribute!
+
+Contributions are accepted via Pull Requests on [Bitbucket][repo]. Sometimes, our free time is very limited and could take a while until we review your pull request, so please be patient while you wait for code review.
+
+We don't mind getting questions, so if you have any, please open a new issue on our [tracker][repo].
+
+## Pull Requests
+
+Here are a few rules which you should follow, in order to ease code review and merging:
+
+1. **Follow [PSR-2 Coding Standard][PSR-2]**
+- **Create feature branches** - We don't pull from your (master|develop) branch!
+- **One pull request per feature** - If you need/want to change more than one thing, please send multiple pull requests.
+- **Consider our release cycle** - We follow [SemVer v2.0.0][semver]. Breaking public APIs is not acceptable.
+- **(Add|Update) tests when applicable.**
+- **Document any change in behaviour** - Update documentation and/or readme file when applicable.
+
+Sometimes you might be asked to also [squash your commits][squash] (*we don't want commits such as `fix 1`, `fix <n>`, `now its working`, etc*). This is done in order to keep a clean and coherent VCS history.
+
+## Running tests
+
+``` bash
+$ composer test
+```
+
+To check against [PSR-2][PSR-2] coding standard:
+
+``` bash
+$ composer style
+```
+
+[repo]: https://bitbucket.org/gentlero/bitbucket-api/overview
+[PSR-2]: https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md
+[squash]: http://www.git-scm.com/book/en/v2/Git-Tools-Rewriting-History#Changing-Multiple-Commit-Messages
+[semver]: http://semver.org/

README.md

@@ -28,7 +28,8 @@ See [http://gentlero.bitbucket.org/bitbucket-api/](http://gentlero.bitbucket.org
 
 ## Contribute
 
-Send pull requests on [Bitbucket](https://bitbucket.org/gentlero/bitbucket-api).
+Please see [CONTRIBUTING](CONTRIBUTING.md) for details.
+
 
 ## Credits