Instant messaging - Internal chat for MYLE user

First Development Requirements:
1) Users will be able to chat with other users in the same system.
2) they can form chat groups for groups of users
3) nothing in the chat can go directly into the patient's chart yet.
4) no sharing of files/documents yet through chat, just chat for now.
5) user's status showing whether they're logged into the EMR (active vs inactive)
6) no cross chatting between MYLE clinics. All kept internally within 1 instance of MYLE