Maintain connected usernames

[gridhead]

Added features

• Maintained a list of username and chatroom in the server side along with their respective WebSocket object
• Added notifications from the server as and when a client joins or leaves the chatroom
• Added elegant messages and notifications when a client leaves a specific chatroom
• Allowed for plain-text logging activity in the server side as and when a client joins or leaves any chatroom
• Kept a list of username and chatroom at the client side as well for latecomers to know who are connected
• Added a word completion suggestive module which continually keeps updating as users join and leave
• Introduced an issue Word completion for usernames updates only after one message is sent after join/leave event #13