fix travis image to filter to master
nsqlookupd: make Registrations non-pointer
nsqlookupd: add tombstone information to /nodes
nsqadmin: display tombstone information on /nodes
Merge pull request #228 from mreiferson/lookupd_dead_228

nsqlookupd/nsqadmin: dead nodes remain in /nodes list
bump to 0.2.22-alpha (update changelog)
first draft of nsq_to_nsq