Allow local authentication mechanism to be disabled in CLI

Previously there was no justification to override the local authentication mechanism in the CLI as all users had the same ability - with the access control work it is now possible the local user will have different permissions to other users so now may want to force alternative authentication mechanisms.

Local authentication will be disabled if one of the following is true: -

• A command line argument '--no-local-auth' is received.
• Both a --user argument is received on the command line.