travis: test iojs, node 0.12
travis: test iojs, node 0.12

feross/bittorrent-tracker,jhiesey/bittorrent-tracker,feross/bittorrent-tracker,jhiesey/bittorrent-tracker,precisit/bittorrent-tracker,LinusU/bittorrent-tracker,prozacchiwawa/bittorrent-tracker