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
Add V(2) here (for other info message as well), the pattern I see in kubectl is to have it 'silent', just scream on errors.