Don't return command in client-server communication

Don't return command in client-server communication

Client already has an id of the message sent to the server. There's no
point in returning the command from server and checking in on the
client's side.

* Stop returning command from server.
* Stop receiving and checking the command in the client.
* Unify naming.

Change-Id: I74bde065c5edcf414820b9c398d18e6bc0d299dd