Add emote autocomplete

[glotchimo]

This one will probably be the most significant addition in v0.2.0 because it'll require an API client and potentially another custom client for working with the BTTV/7TV APIs. What we'd want to do though is load in emote names at runtime and add them to the username autocomplete system. I don't think we care about displaying the actual images considering how non-portable that is and how much of a pain it might be to keep up a server for supporting that.