Have quiescing ticker optionally call a function.

Maybe I should only have it do that since that's how I'm using it.
Slightly more reliable ticker test.

Increasing parallelization caused it to drop a lot more.
Moved periodic function application into a new thing.
Removed quiescing_ticker
We've got a config, let's pass that instead of lots of args
Close the bucket observer when shutting down a bucket.
Close up buckets after tests.

cbugg: close bug-337
A more efficient tool for creating test buckets.