Removing dependency on trove models in the guest agent

Reasons:
 - The guest agent is importing backup models and agent
   heartbeat, this triggers the all of the trove database
   setup logic which bloats the guest process on the host.

 - Moving the state to its own module and removing an unused
   function decreases the memory usage by about 15 - 20 megs.

Closes-Bug: #1375311
Change-Id: I126c0b89c170b325d85b3f09afca399b4f5de9e8
Merge "Removing dependency on trove models in the guest agent"