Change Room structure so we can look up clients in the room more efficiently

[shankarammai]

Possibly change structure to below so we can efficiently get clients of a room.

type Room struct {
    Id      string
    Name    string
    Clients map[string]*Client
    Creator string
}

This can possibly improve performance in the clean up code when clients leaves the room.
When sending room data to customers only send [string,string].