MUC support

[andersevenrud]

Originally opened in os-js/OS.js#729:

Hello,
I tried getting MUC in strophe js OS.js but it doesn't seem to work. Does OS.js support the Multi User Chatroom?

Required changes:

• MUC Plugin
• MUC Room join functionality
• Leave room on close
• Message handler
• Roster handler
• Presence handler
• Invitation
• Chat window roster support w/presence (column to the right)
• Chat window menubar on muc (leave room, invite, etc)

Pull-request: #3

[andersevenrud]

@Pratikk460

It's possible to connect to a server that supports MUC, but currently it's only possible to have a two person dialog.

In order for a proper "chat room" support this application needs to use something like https://github.com/strophe/strophejs-plugin-muc and then get a new chat window implementation (that shows all users in a list, options for invites etc).

The main UI also needs to be updated to support joining or leaving a list of available rooms, as well as create a new one.