Initial version of github compatible hooks
Initial set of tests for github compatible web hooks
Improve GitHub compatible webhooks

 * Remove the global github_compatible_hooks configuration
 * Add github_compatible flag to the WebHook model
 * Add pusher information to the hook payload
Fixes for github compatible webhooks and related tests
Make WebHook.github_compatible_data use hash with indifferent acccess so it works properly with backgorund services as well