errors should fail builds

[shreddedbacon]

In most cases of the controller handling a build, any error encountered after the build has been accepted should result in the build failing.

Currently the behaviour of the controller is to try and reconcile again which results in the error. Failing builds would be more appropriate, and sending a build log message with a brief description of what went wrong to aid in support troubleshooting.

[shreddedbacon]

closing as duplicate of #52