task manager using messages

* First pass, adapt singleton task manager to process messages and run
jobs based on events instead of a busy loop.
* Still need to make message handing run in celery, not in a consumption
loop

awx/api/views.py

@@ -2290,6 +2290,7 @@ class JobTemplateLaunch(RetrieveAPIView, GenericAPIView):
 
         new_job = obj.create_unified_job(**kv)
         result = new_job.signal_start(**kv)
+
         if not result:
             data = dict(passwords_needed_to_start=new_job.passwords_needed_to_start)
             new_job.delete()