Branch build status tags

[nateabele]

The branch index should display build status tags to the left of each branch name. The configuration should allow you to specify a URL that can be templated out with each branch with the image tag, i.e. http://buildservice.com/tag?branch={branch}.

Side note: I'm blindly assuming we can get these from Jenkins...?

[nateabele]

cc: @gavD

[gavD]

yes, I'm pretty sure we can get the status of the upstream commit