Change verification of privileges

Change verification of privileges

Now, the privileges are checked depending on the message
type received.

This implementation requires DCM daemon to receive
& deserialize the message 1st before checking client privileges.

This is required by the introduction of DCM EXT API which can be guarded
by specific privilege (or none) for each backend method.

Change-Id: Iaaae1bc220e497f2488d8d2700a5334fa14b61b6