better 'retry job' behavior

[dcramer]

we need to decide what to do when a job is retried

simplest/most accurate answer would be to orphan the job (or just straight up delete it), and create new rows for it. if we orphaned it we could still track its visibility and build, but it wouldn't show up in the UI, and its build number would need reclaimed

[dcramer]

I think I'm good with adding something like 'orphaned = True/False' in the db to resolve this. It's easier than removing rows.

[dcramer]

internally it seems travis just clears the results and re-uses the same ID -- lets just take the same approach

[jan-auer]

This has already been solved with #44, no?