Bug 1133580 - Autophone - update to worker.py, r=mcote.

- clean up device error/disconnection/disable states
- add new FETCHING state.
- move compatible job detection into autophone.py
- delete tests from the jobs database as they are completed.
- use test status RETRY when a test must be retried while
  creating a new job for the test(s) to be retried.
- process retrigger, cancel job actions

phonestatus.py

@@ -6,6 +6,7 @@ class PhoneStatus(object):
 
     IDLE = 'IDLE'
     CHARGING = 'CHARGING'
+    FETCHING = 'FETCHING BUILD'
     INSTALLING = 'INSTALLING BUILD'
     WORKING = 'WORKING'
     REBOOTING = 'REBOOTING'