Use recommended setup for Celery

Note: does it improve anything?

gargantext/__init__.py

+from .celery import app as celery_app

gargantext/celery.py

+"""
+Setup the Celery instance (see also gargantext/__init__.py) that will be
+used by all shared_task.
+
+This is the recommended way:
+http://docs.celeryproject.org/en/3.1/django/first-steps-with-django.html
+"""
+
+import os
+from celery import Celery
+
+os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'gargantext.settings')
+
+from django.conf import settings #noqa
+
+app = Celery('gargantext')
+app.config_from_object('django.conf:settings')
+app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)

gargantext/settings.py

@@ -34,9 +34,12 @@ ALLOWED_HOSTS = ["localhost", ".gargantext.org", ".iscpif.fr",]
 
 import djcelery
 djcelery.setup_loader()
+
 BROKER_URL = 'amqp://guest:guest@localhost:5672/'
-CELERY_ACCEPT_CONTENT = ['pickle', 'json', 'msgpack', 'yaml']
 
+CELERY_ACCEPT_CONTENT = ['pickle', 'json', 'msgpack', 'yaml']
+CELERY_TIMEZONE = 'Europe/Paris'
+CELERYBEAT_SCHEDULER = 'djcelery.schedulers.DatabaseScheduler'
 CELERY_IMPORTS = (
                     "gargantext.util.toolchain",
                     "gargantext.util.crawlers",