Added contribution guide

Author: weierophinney

CONTRIBUTING.md

@@ -0,0 +1,74 @@
+# CONTRIBUTING
+
+Apigility and related modules (of which this is one) are open source and licensed
+as [BSD-3-Clause](http://opensource.org/licenses/BSD-3-Clause). Contributions
+are welcome in the form of issue reports and pull requests.
+
+All pull requests should include unit tests when applicable, and should follow
+our coding standards (more on these below); failure to do so may result in
+rejection of the pull request. If you need help writing tests, please ask on the
+developer mailing list and/or in IRC.
+
+## RESOURCES
+
+If you wish to contribute to Apigility modules, please be sure to
+read/subscribe to the following resources:
+
+ -  [Coding Standards](https://github.com/zendframework/zf2/wiki/Coding-Standards)
+ -  [ZF Git Guide](https://github.com/zendframework/zf2/blob/master/README-GIT.md)
+ -  [Apigility developer mailing list](http://bit.ly/apigility-dev)
+ -  Apigility developer IRC channel: #apigility-dev on Freenode.net
+
+If you are working on new features, refactoring an existing module, or proposing
+a new module, please send an email to the developer mailing list.
+
+## REPORTING POTENTIAL SECURITY ISSUES
+
+If you have encountered a potential security vulnerability in any Apigility
+module, please report it to us at [[email protected]](mailto:[email protected]).
+We will work with you to verify the vulnerability and patch it.
+
+When reporting issues, please provide the following information:
+
+- Module(s) affected
+- A description indicating how to reproduce the issue
+- A summary of the security vulnerability and impact
+
+We request that you contact us via the email address above and give the project
+contributors a chance to resolve the vulnerability and issue a new release prior
+to any public exposure; this helps protect Apigility users, and provides them
+with a chance to upgrade and/or update in order to protect their applications.
+
+For sensitive email communications, please use 
+[our PGP key](http://framework.zend.com/zf-security-pgp-key.asc).
+
+## RUNNING TESTS
+
+First, use [Composer](https://getcomposer.org) to install all dependencies:
+
+```console
+$ composer install
+```
+
+To run tests, use the PHPUnit executable installed by Composer:
+
+```console
+$ ./vendor/bin/phpunit
+```
+
+## CODING STANDARDS
+
+While Apigility uses Zend Framework 2 coding standards, in practice, we check
+standards using [php-cs-fixer](https://github.com/fabpot/PHP-CS-Fixer) (which is
+installed via Composer with other dependencies). To check for CS issues:
+
+```console
+$ ./vendor/bin/php-cs-fixer fix . --dry-run
+```
+
+This will report CS issues. Alternately, you can have the tool fix them for you
+by omitting the `--dry-run` switch:
+
+```console
+$ ./vendor/bin/php-cs-fixer fix .
+```