Background: the chat application lets users toggle on/off to be in/out of chat
rooms. Notifications are only received when a user is in a chat room.
Currently: typing '@@' when sending a message brings up a list of all users on
the application. Currently, this will send a direct message to the individual
selected this way, but only if that individual is in the chat room. Request:
use '@@' to directly 'pull' someone from the list into the room, if they
aren't already in the room, then send the direct message. In this way, users
should be able to pull other users into conversations.