Port invitesifrom tokeninput to new select2

Conflicts:
	app/assets/stylesheets/application.css
	app/views/invites/invite_room.html.haml
Refactor invite_room.js and remove last references to tokeninput

invites/invite_room was not binding the events correctly when the modal was
opened.
Also removed all last references to tokeninput except the ones in chat.js

refs #275