JobType Rework

This pull request is a rework of the base `JobType` class and associated modules.  The changes here are based on a thread on [discuss@pyfarm.net](https://groups.google.com/a/pyfarm.net/d/msg/discuss/er2e44kiPBE/JwVnOn43U-4J).
Neither do I and it's definitely something I'm going to be fixing soon.  Both start and stop have the same problem at the moment where what we do internally versus was we allow to be override is not well broken down yet.  Additionally we don't have a few methods that provide the idea of pre or post operations like we've discussed.  None of this will be hard to fix....it just needs to be done.