List NotImplementedError as client exception

Mark NotImplementedError as a client exception for the
get_console_output rpc api method.  This is an expected result if the
driver does not implement this functionality.  If raised, the rpc layer
should not log a traceback.

Change-Id: I60747bf48c378053eb0d36337fcc26201b4840f9
Merge "List NotImplementedError as client exception"