Now depends on billiard 2.7.3.28
Retry policy max_retries should be 3, not 100.  Closes #1305
Updates Changelog
Bumps version to 3.0.19
Remove outdated/uneeded files to make dist smaller
Merge branch '3.0'

Conflicts:
	Changelog
	README.rst
	celery/__init__.py
	celery/app/defaults.py
	celery/worker/consumer.py
	docs/includes/introduction.txt
	requirements/default.txt
	setup.cfg
Py3 fixes
flakes
tests passing
Do not apply Django fixups if Django is not installed (but show warning).  Related to #1311
Temporary fix for #1306
Fixes NameError
maxtasksperchild -> max_tasks_per_child
celery command cannot catch TypeError
Fix for fileno when long
Removes hack fix solved by asynwrite branch
Fix 'celery migrate ...'

consume_from isn't passed by the command so grab the queues from the
keys of queues if consume_from is None
Merge pull request #1315 from dctrwatson/fix-migrate

Fix 'celery migrate ...'
chain: must accept generator argument (regression). Closes #1319
Missing parenthesis