Kill test process after set limit of time and consider it a FAIL

[leto]

I recently ran into an issue where my custom "builder" script ran into an infinite wait loop, and basically clogged Jitterbug, making it wait forever.

Jitterbug should be smarter than this. So we need a configuration key that specifies a reasonable maximum amount of seconds for any test suite. There should be a global config key as well as a per-repo key.