Added connection.Pool.acquire_channel context manager.
Added connection.Pool.acquire_channel context manager.

tkanemoto/kombu,jindongh/kombu,numb3r3/kombu,disqus/kombu,Elastica/kombu,ZoranPavlovic/kombu,romank0/kombu,bmbouter/kombu,alex/kombu,urbn/kombu,pantheon-systems/kombu,romank0/kombu,depop/kombu,andresriancho/kombu,Elastica/kombu,mathom/kombu,disqus/kombu,tkanemoto/kombu,depop/kombu,mverrilli/kombu,WoLpH/kombu,xujun10110/kombu,numb3r3/kombu,mverrilli/kombu,iris-edu-int/kombu,daevaorn/kombu,jindongh/kombu,ZoranPavlovic/kombu,alex/kombu,pantheon-systems/kombu,celery/kombu,daevaorn/kombu,cce/kombu,cce/kombu,bmbouter/kombu,mathom/kombu,andresriancho/kombu,iris-edu-int/kombu,WoLpH/kombu,xujun10110/kombu