Read Receipts

[sanket0896]

• on ADD_MESSAGE, message "created" receipt
• on server ADD_MESSAGE receive, message "uploaded" receipt
• on target MESSAGE_RECEIVED, message "received" receipt
• on target MESSAGE_READ, message "read" receipt
• Add a unique message Id to each message
• add messageStatus to message state
• add UI icon for "created" receipt
• add UI icon for "uploaded" receipt
• add UI icon for "received" receipt
• add UI icon for "read" receipt