[WIP] Add option to cancel a build

~~this is a rough draft, I'm actively working on it.. so it may throw errors and it may have dirty code.~~

   - Add cancelling and cancelled status for builds
   - Remove pod and update builds to cancelled when a cancel event was triggered for the build
We're in the build factory, I don't see any value with doing this. You'd have to rename the other method to `CreateBuildPod` as well which isn't necessary IMHO.