Add support for Apache Zookeeper as a transport
Merge remote-tracking branch 'upstream/master'

Conflicts:
	kombu/transport/zookeeper.py
Syncing with master
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Redis: Ignore if queue not in round-robin cycle
Tests passing
Py3 atexit._exithandlers missing
Fixes msgpack tests
Updates Changelog
Bumps version to 2.5.12
Merge remote-tracking branch 'upstream/master'
Get Zookeeper transport working again

This had to be updated to the new Kazoo APIs.
Also Kazoo has a recipe for Queues. Migrated to that.
amqp: Merge transport options
Merge branch 'mahendra/zookeeper'
Merge branch '2.5'

Conflicts:
	Changelog
	README.rst
	kombu/__init__.py