Buildbox Service Integration

Hi, I've added integration with my CI product https://buildbox.io. I've matched my service with the GitLab CI service. I've shipped GitLab support to Buildbox today, which includes the endpoints necessary for the merge request status and badges. I needed access to merge requests events so I refactored the service hooks to include the events and included them in merge request changes. I hope that's OK.

Please let me know if theres anything I need to do to get this merged into master.

Thanks! Here are some images of how it all looks:

![image](https://cloud.githubusercontent.com/assets/25882/3965505/b2ac6578-2797-11e4-94f3-a5a7892db85a.png)

![image](https://cloud.githubusercontent.com/assets/25882/3965508/b737369a-2797-11e4-9a5f-70d164366d45.png)

![image](https://cloud.githubusercontent.com/assets/25882/3965510/ba34aec2-2797-11e4-8b04-1b95a53acc2c.png)

![image](https://cloud.githubusercontent.com/assets/25882/3965511/be24753a-2797-11e4-80c8-01aa63518aeb.png)
I'm not sure if this is necessary, or wanted. The current behavior for GitLab CI services is the hook actually triggers on the event (default `push`). So the build is already in progress by the time a merge request is created. In this case you're going to fire the build again when a merge request is created, when it's already been triggered for the latest commit after a push event. For merge requests GitLab grabs the latest commit sha and checks the CI status on that. The build might have already been completed by that point. Does that make sense?