architecture: separate cmd parsing and authentication

[rhynolite]

Command parsing and authentication must be separated.

Instaed of relying on

  CmdLogin cmd = new CmdLogin();

   cmd.parse(args);

to authenticate, the code should look like this:

  CmdLogin cmd = new CmdLogin();
  cmd.parse(args);
                Credentials auth = Authentication.checkCredentials(cmd);

The Credentials object will contain all auth-related information

The CMD objects will be responsible on for cmdline parsing and storing the data - no functionality besides the "main" function.