Advertised set-x-token method in do_fork and set_pagure_issue
    
    The new commmands `set-distgit-token` and `set-pagure-token` were
    added but were not sufficiently advertised in the case that
    the user's API key did indeed fail. This change fixes this, adding
    the advertisement of the command to the relevant command failures.
    
    Relates: #192
    JIRA: RHELCMP-58
    Merges: https://pagure.io/fedpkg/pull-request/446
    
    Signed-off-by: James Kunstle <jkunstle@redhat.com>