* [NOD-381] Publish transaction messages to MQTT
* [NOD-381] Remove redundant variable
* [NOD-381] Send payload as string
* [NOD-381] Add Error handling
* [NOD-381] Respond with TransactionResponse
* [NOD-381] Use transactionResponse for notifications
* [NOD-381] Move code to appropriate places
* [NOD-381] Pass raw block instead of txId
* [NOD-381] Add comments to public functions
* [NOD-381] Remove print statement
* [NOD-381] Pass transaction instead of block; Use pointers so default will be nil;
* [NOD-381] Use pointers so value could be nil
* [NOD-381] Change variable name
* [NOD-381] Set QoS to 2
* [NOD-381] Move isConnected to MQTT, so client won't have to worry about it; General code refactors;
