Update to use DatWorkerPool instead of it's own

This updates DatTCP to use DatWorkerPool instead of it's own.
This replaces all the worker pool logic in DatTCP. This includes
some minor changes to work with DatWorkerPool, but all
functionality remained as it was previously.
Merge pull request #18 from redding/jcr-use-dat-worker-pool

Update to use DatWorkerPool instead of it's own