Moves celery.worker.hub here as kombu.async

This is not really done yet, but it will have to live here eventually
as the async transports will want to register with a eventloop.
virtual queue_declare now returns namedtuple
Removes kombu.log.anon_logger
pypy did not like this change
Sem data cannot be set
flakes
Async API now closer to Tulip
flakes
Fixes TypeError
Renamed serialization.encode/decode -> .dumps, .loads
Removes amqp version check
Adds kombu.message.Message
Replaced StdConnectionError+StdChannelError with amqp.ConnectionError+amqp.ChannelError
Cosmetics
Change redis transport to rpush rather than lpush messages on the queue when they are restored to make the ack emulation more consistent with the amqp transport.
Adds Mark Lavin to AUTHORS
Redis: reject+requeue should restore at beginning (Related to #254)
Adds kombu.async.maybe_block context
Do not check heartbeats when in blocking sections
Merge branch 'master' into asyncmove

Conflicts:
	kombu/async/hub.py
	kombu/connection.py
	kombu/serialization.py