celery: initial release
- Adds Celery support to Invenio by defining a custom Celery loader that will load tasks defined in invenio.*_tasks modules. (closes #1458)
- Requires Python 2.5+ and Celery 3.0.x
Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
Reviewed-by: Jiri Kuncar <jiri.kuncar@cern.ch>