Add private rooms

[AmitBerg]

Add private rooms that will inherit from Room model.

• Users would be able to chat one on one.
• Users would be able to chat with groups of people.

The idea is there would be two tabs on the Navbar (or in the index page):
1.Public rooms - anyone can chat in those rooms, they just need to have a user on the site.
2.Private Rooms - you can chat only in the rooms that you are in. You can join an existing room by answering a join request, or create one and invite people (maybe add a limit to how many private rooms a user can create).

The PrivateRoom model can have a property to a Group (Fk).