Create API interface for Queue Callers

Right now we are using the sqlalchemy backend, until we build out the
redis model. We also remove any redis dependencies, since we don't
actually use it now.

Change-Id: I0fca1387cc9d4fc4348fa0bc141a41cd7c8ed339
Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>