Fix race condition in secondary watcher claim management.

The problem was that once we started shutting down, we shut down the claim manager so we
weren't updating our claims any more.  If finishing processing the current job took too long,
then someone else could steal the job from under us.  This keeps the claim manager running until
we are actually shutting down to avoid that.
Remember to start the claimTimeManagerThread too!
Merge pull request #16 from socrata/marcs/secondary-watcher-claim-management-race

Fix race condition in secondary watcher claim management.