added vhost, exchange_name and queue_name options so carbon-cache  can be pointed to different queue server, exchange and queue.
added vhost, exchange_name and queue_name options so carbon-cache  can be pointed to different queue server, exchange and queue.

deniszh/carbon,cbowman0/carbon,JeanFred/carbon,benburry/carbon,krux/carbon,graphite-server/carbon,criteo-forks/carbon,deniszh/carbon,pu239ppy/carbon,piotr1212/carbon,iain-buclaw-sociomantic/carbon,iain-buclaw-sociomantic/carbon,cbowman0/carbon,benburry/carbon,lyft/carbon,criteo-forks/carbon,kharandziuk/carbon,graphite-project/carbon,protochron/carbon,xadjmerripen/carbon,kharandziuk/carbon,pratX/carbon,mleinart/carbon,mleinart/carbon,obfuscurity/carbon,pratX/carbon,obfuscurity/carbon,pu239ppy/carbon,graphite-server/carbon,JeanFred/carbon,johnseekins/carbon,xadjmerripen/carbon,krux/carbon,protochron/carbon,lyft/carbon,graphite-project/carbon,piotr1212/carbon,johnseekins/carbon