Replace django-celery with base Celery (#791)

Update celery tasks to new style & remove djcelery
Vanilla celery + django-celery-beat take over the role of djcelery. Task schedules are consolidated into settings instead of residing in code.
Update docs and example supervisor configs.

alliance_auth/tests/test_settings.py

@@ -4,14 +4,10 @@ Alliance Auth Test Suite Django settings.
 
 import os
 
-import djcelery
-
 from django.contrib import messages
 
 import alliance_auth
 
-djcelery.setup_loader()
-
 # Use nose to run all tests
 TEST_RUNNER = 'django_nose.NoseTestSuiteRunner'
 
@@ -40,7 +36,7 @@ INSTALLED_APPS = [
     'django.contrib.messages',
     'django.contrib.staticfiles',
     'django.contrib.humanize',
-    'djcelery',
+    'django_celery_beat',
     'bootstrapform',
     'authentication',
     'services',