Replace global Conf mangling with monkeypatch

The test suite, especially for the brokers, was heavily dependant on the
success of the tests preceeding it to pass. This commit should eliminate
that dependency and allow tests to fail without affecting others.
It also removes the need to cleanup globals manually after a test.

django_q/tests/test_scheduler.py

@@ -13,17 +13,13 @@ from django_q.tasks import Schedule, fetch, schedule as create_schedule
 
 
 @pytest.fixture
-def broker():
-    Conf.DISQUE_NODES = None
-    Conf.IRON_MQ = None
-    Conf.SQS = None
-    Conf.ORM = None
-    Conf.DJANGO_REDIS = 'default'
+def broker(monkeypatch):
+    monkeypatch.setattr(Conf, 'DJANGO_REDIS', 'default')
     return get_broker()
 
 
 @pytest.mark.django_db
-def test_scheduler(broker):
+def test_scheduler(broker, monkeypatch):
     broker.list_key = 'scheduler_test:q'
     broker.delete_queue()
     schedule = create_schedule('math.copysign',
@@ -117,7 +113,7 @@ def test_scheduler(broker):
     # ONCE schedule should be deleted
     assert Schedule.objects.filter(pk=once_schedule.pk).exists() is False
     # Catch up On
-    Conf.CATCH_UP = True
+    monkeypatch.setattr(Conf, 'CATCH_UP', True)
     now = timezone.now()
     schedule = create_schedule('django_q.tests.tasks.word_multiply',
                                2,
@@ -130,7 +126,7 @@ def test_scheduler(broker):
     schedule = Schedule.objects.get(pk=schedule.pk)
     assert schedule.next_run < now
     # Catch up off
-    Conf.CATCH_UP = False
+    monkeypatch.setattr(Conf, 'CATCH_UP', False)
     scheduler(broker=broker)
     schedule = Schedule.objects.get(pk=schedule.pk)
     assert schedule.next_run > now