function to set a build revision
add LibGit2Sharp
get SHA for build if there isn't already one
don't require a SHA for forced builds
add button to build ref for failed builds
Merge pull request #39 from half-ogre/half-ogre/25-dont-require-sha

Don't require a SHA for a forced build
fix code thats gets the HEAD SHA to handle PRs
don't try to update GitHub status if there's no SHA
don't show rebuild SHA form if there's no SHA
give the view a better name, describing what it is
handle a null SHA when showing a build
refactor so the response model creation can be reused
add POST /builds
add form to start a new build
actually check for an empty value
style errors
Merge pull request #41 from half-ogre/half-ogre/26-force-builds

Add a form to start a new build
remove URL from builds
Merge pull request #44 from half-ogre/half-ogre/remove-url-from-builds

Remove URL from builds
fix manual builds for branches other than master