settings.py,__init__.py: update celery configuration

- register 'custom-json' as kombu serializer
- set 'custom-json' as the default celery serializer
- fix the result backend configuration
- import settings from django.conf (it allows using different settings modules)
- celery 3.1.19 is NOT supported due to a bug in the redis backend (only affects UNIX-domain sockets, see: celery/celery#2903)

demos/demos/__init__.py

@@ -1,8 +1,17 @@
 # File: __init__.py
 
-from .settings import base
+from django.conf import settings
 
 if set(base.DEMOS_APPS).intersection(['ea', 'bds', 'abb']):
-    from .settings.celeryapp import app as celery_app
+
+    import json
+
+    from functools import partial
+    from kombu.serialization import register
+    from demos.common.utils.json import CustomJSONEncoder
+
+    register('custom-json', partial(json.dumps, cls=CustomJSONEncoder), \
+        json.loads, 'application/x-custom-json', 'utf-8')
+
 
 #eof

demos/demos/settings/base.py

@@ -320,6 +320,9 @@
 
 
 # End of demos-specific configuration
+CELERY_TASK_SERIALIZER = 'custom-json'
+CELERY_RESULT_SERIALIZER = 'custom-json'
+CELERY_ACCEPT_CONTENT = ['custom-json', 'json', 'msgpack']
 
 if DEVELOPMENT:
     DEBUG = True