replace celery task decorators with a kombu-based publisher

this commit implements the bulk of `awx-manage run_dispatcher`, a new
command that binds to RabbitMQ via kombu and balances messages across
a pool of workers that are similar to celeryd workers in spirit.
Specifically, this includes:

- a new decorator, `awx.main.dispatch.task`, which can be used to
  decorate functions or classes so that they can be designated as
  "Tasks"
- support for fanout/broadcast tasks (at this point in time, only
  `conf.Setting` memcached flushes use this functionality)
- support for job reaping
- support for success/failure hooks for job runs (i.e.,
  `handle_work_success` and `handle_work_error`)
- support for auto scaling worker pool that scale processes up and down
  on demand
- minimal support for RPC, such as status checks and pool recycle/reload

awx/main/tests/functional/conftest.py

@@ -14,7 +14,6 @@ from django.core.urlresolvers import resolve
 from django.utils.six.moves.urllib.parse import urlparse
 from django.utils import timezone
 from django.contrib.auth.models import User
-from django.conf import settings
 from django.core.serializers.json import DjangoJSONEncoder
 from django.db.backends.sqlite3.base import SQLiteCursorWrapper
 from jsonbfield.fields import JSONField
@@ -66,17 +65,6 @@ def swagger_autogen(requests=__SWAGGER_REQUESTS__):
     return requests
 
 
-@pytest.fixture(scope="session", autouse=True)
-def celery_memory_broker():
-    '''
-    FIXME: Not sure how "far" just setting the BROKER_URL will get us.
-    We may need to incluence CELERY's configuration like we do in the old unit tests (see base.py)
-
-    Allows django signal code to execute without the need for redis
-    '''
-    settings.BROKER_URL='memory://localhost/'
-
-
 @pytest.fixture
 def user():
     def u(name, is_superuser=False):