This displays useful error messages when passing invalid or expired API tokens

to a command. Previously, if you passed an API token that was expired or

invalidated it would silently fail and then prompt the user to enter a

username and password.

Tested rbt api-get, and rbt login commands with

  the --api-token option. Used valid, invalid and expired tokens.
Tested the above commands with valid and invalid --username and

--password options.