Should not send replies for cast messages

Cast messages will not contain a msg_id  and we're currently
sending messages to the default excahgne with empty msg_id.
In order to fix it we should not send replies if there is no
msg_id in message.

Change-Id: I5b1142029d2c718c3929cf6cf1f6e958b95a5c96
Closes-bug: #1355058
Merge "Should not send replies for cast messages"