Refactor event emitter to not use event partials

event emitter now caches to memcache where it is eventually picked up
by the stdout event emitter. This obviates event reassembly in the
callback receiver.

awx/main/tasks.py

@@ -822,6 +822,7 @@ class RunJob(BaseTask):
         env['MAX_EVENT_RES'] = str(settings.MAX_EVENT_RES_DATA)
         env['CALLBACK_QUEUE'] = settings.CALLBACK_QUEUE
         env['CALLBACK_CONNECTION'] = settings.BROKER_URL
+        env['CACHE'] = settings.CACHES['default']['LOCATION'] if 'LOCATION' in settings.CACHES['default'] else ''
         if getattr(settings, 'JOB_CALLBACK_DEBUG', False):
             env['JOB_CALLBACK_DEBUG'] = '2'
         elif settings.DEBUG:
@@ -1029,6 +1030,9 @@ class RunJob(BaseTask):
 
             def job_event_callback(event_data):
                 event_data.setdefault('job_id', instance.id)
+                cache_event = cache.get('ev-{}'.format(event_data['uuid']), None)
+                if cache_event is not None:
+                    event_data.update(cache_event)
                 dispatcher.dispatch(event_data)
         else:
             def job_event_callback(event_data):