PikaMessageInterface and NoMessageInterface.  The BalsamJobReceiver and
BalsamStatusSender interact with their respective MessageInterfaces
through a few public methods that encapsulate all the protocol-specific
methods.  This should make it easier to add new job sources like HTTP

- Updated syntax for exception handling from 2 to 3
- Replaced "Queue" with "queue" module
- Broke ConnectionParameters -- changed to 'localhost' for testing
- Identified BUG: argojob = ArgoJob.objects.get(job_id=sub.job_id)

Allow some configuration parameters to be in error: Catch them later as needed (e.g. when configuring Balsam to talk to Argo)