Code review comment for lp:~rockstar/launchpad/branch-scanner-prep

Hi Edwin-

  This branch adds a JobPruner to the daily garbo script. It removes any jobs
that have a date_finished of more than thirty days. This is needed for the
next few branches that turn the scanner into a job. If we didn't do this, the
job table would get out of hand really quick.

  To test, do:
   bin/test -vvc canonical.launchpad.scripts.tests.test_garbo \
   TestGarbo.test_JobPruner

 reviewer edwin-grubbs

Cheers,
Paul