Work Queue Cleanup

Major cleanup of work_queue_pool and work_queue_worker.

work_queue_pool now queries the catalog for masters with a given project name (regex), computes the desired number of workers, and submits them with the same project name (regex).

work_queue_worker now clearly queries for the list of matching masters and tries them in a random order.  The worker no longer queries "wq_pool" records from the catalog for configuration.

There are still some problems here that need to be addressed:
- timeouts are used inconsistently, esp regarding when to disconnect after periods of idleness.
- accounting for resources locally doesn't look right, esp dividing by the number of workers.


What was wrong with timestamp_t?

In any case, I prefer int64_t or one of its variations.