Thanks to investigations by@Furtif, this PR adds clarity to the abort message which happens if there's no user or project information after options and configurations have been parsed.

Before this change, the abort would print out only the name of the program and the "usage", which was incredibly bare.

• Explain to the user why their invocation did not work: "Tell us which user and project to work on. Options --user and --project, or settings to that effect."

See#577