Renames Result.serializable()/from_serializable -> Result.as_tuple()/result_from_tuple
Documents -Ofair
Fixes typo
Adds new worker_process_shutdown signal (Closes #1595)
Cosmetics for #1595
Fix typo in header comment of celery.canvas.

should is currently used instead of should not
Warn against using revoke+terminate programatically
Fixes typo in revoke command
Wording
Asynpool: Fixes race condition when child proces terminated fast
Fixes tests (requires kombu master)
Merge pull request #1613 from twright/patch-1

Fix typo in header comment of celery.canvas.
Adds correlation_id to multiprocessing ApplyResult
Small doc changes
Fixes compat with billiard
Make sure pool does not put back job multiple times
.asynpool is here temporarily
Now depends on Kombu 3.0.3
Now depends on billiard 3.3.0.1
Fixes pickle of schedule and ScheduleEntry classes.  Closes #1603