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)
My thinking was that if we at Buildbox offer a self hosted solution, then you'd just change the ENV variable and you could point it at the new host, but in reflecting on that, that's probably not coming any time soon, so I might just rip that out.