nsqd: Topic messagePump need not get channels initially
nsqd: Topic messagePump need not get channels initially

channels always added async along with notification on channelUpdateChan

sparklxb/nsq,jehiah/nsq,bitly/nsq,jehiah/nsq,jehiah/nsq,sparklxb/nsq,mreiferson/nsq,mreiferson/nsq,ploxiln/nsq,rpau/nsq,bitly/nsq,nsqio/nsq,bitly/nsq,nsqio/nsq,nsqio/nsq,bitly/nsq,ploxiln/nsq,ploxiln/nsq,jehiah/nsq,mreiferson/nsq,sparklxb/nsq,nsqio/nsq,sparklxb/nsq,rpau/nsq,sparklxb/nsq,mreiferson/nsq,nsqio/nsq,mreiferson/nsq,ploxiln/nsq,jehiah/nsq,rpau/nsq,rpau/nsq,rpau/nsq,ploxiln/nsq,bitly/nsq