Add files for demonize celery via systemd.
Edit tutorial for demonizing
Fix tutorial
Fix tutorial
More fixes
Fix
Add in tutorial
Remove celery config file
The help about environment variables
The help about environment variables
Commented out the "Environment" by default
Trace: Must also find pickleable type
[->3.0] LimitedSet.purge must ignore KeyError
Attempting to resolve issue-1387 by first declaring local pid_file= to null in check_status()

Found that if _get_pid_files returns more than one file the local pid_files=`_get_pid_files` line 161 results in a bad variable name on ubuntu 12.04.
Fixed problem #1373 a unicode decode error caused by utf-8 characters in the platform
Should include cwd when importing custom loader
itermro: Forgot to yield value
[docs] Adds note that ETA/countdown tasks are not affected by prefetch limits.  Closes #1302
Updates Changelog for 3.0.20
Fixes broken example in task userguide (Issue #1357).

Probably haphazardly converted from `callback passing style` to using chains.