making AioConnection.connect a coroutine and other small fixes

[MattBroach]

This PR is really more of a stopgap until @zinsserzh implements what he's planning in this issue, but I was butting up against some of the very limitations he was talking about and decided to roll out a patch to address them in the short term. Specifically:

• As suggested, makes AioConnection.connect a coroutine, which allows for reconnecting after loop.run_forever has been called. Since overwriting the AioSimpleIRCClient.connect function to call loop.run_until_complete was pretty easy, this change was actually minimally disruptive
• Adds a AioConnection.disconnect call to the IrcProtocol in the connection_lost function
• Cleans up the various print functions I stupidly left in last time

[jaraco]

Looks good. Mind adding a CHANGES.rst entry? 0.1 bump probably.

[MattBroach]

Of course! Updated.

[jaraco]

Going out as 16.4. Thanks!