Enable deployment step for successful projects

This change set provides support for deployment.
You can provide a deployment script in the build settings.

If the latest build for a commit is successful you can *manually* hit the deploy button and let one
of the runners deploy your project. After successful deployment the status will change to _deployed_.
If the deployment fails the status will be _successful_ again.

Here are some screenshots:
![deploysettings](https://f.cloud.github.com/assets/448282/1572239/864e0628-5117-11e3-8fd4-678965c622d3.PNG)
![deploy_builds](https://f.cloud.github.com/assets/448282/1572240/866d2602-5117-11e3-8643-6ebf11294849.PNG)