update for aiohttp 0.10.2
Roost.redisplay -> SnipeBackend.redisplay

So it can be used by other backends that, like, get messages
generate a useragent string
make our websocket helper a bit more general

(when connecting to a server-sends-first socket, if you don't turn off
'read_until_eof', the wrong parser will consume the initial server output)
incorrect, incomplete, and annoying irccloud read support