Fix bug 467346 - Adding prev link to revision history
Ensure the pre_delete signal is only sent once on Document deletion.

Previously it was being sent twice in some circumstances -- once by
Document.delete() and once by the parent delete() method.
add temporary task logger to file for debugging
Merge pull request #2416 from groovecoder/celery-task-logging

add temporary task logger to file for debugging
enable new kuma_task_logger handler in celeryd
Merge pull request #2417 from groovecoder/celeryd-hijack-root-logger

enable new kuma_task_logger handler in celeryd
Merge pull request #2413 from ubernostrum/document-delete-signal

Ensure the pre_delete signal is only sent once on Document deletion.
remove temporary k.task logger
Enabled task sent event.
Merge pull request #2412 from iakshay/bug-467346

Fix bug 467346 - Adding prev link to revision history
Merge pull request #2419 from jezdez/celery-events

Enabled task sent event.
Merge pull request #2418 from groovecoder/remove-tmp-task-logger

remove temporary k.task logger