[WIP] XEP-0045 Multi-User Chat

This is a implementation of #5.

http://xmpp.org/extensions/xep-0045.html

I opened this pull request to collect some requirements for the upcoming 2.0 release:

**Must have:**
- [ ] Discover server support
- [ ] Create room
- [ ] Join room
- [ ] Password protected rooms
- [ ] Groupchat
- [ ] Groupchat window design
- [ ] Close room
- [ ] Leave room
- [ ] Handle nickname conflict

**Should have:**
- [ ] Show member list
- [ ] Querying for Room Information
- [ ] Discover Rooms