Add -p, —prototype command line option to select different repositories from the Carbon Five default

 - Enable the option that was there
 - In fetch_latest_tag:
    - Use parameter to method rather than instance variable for repo
    - Check that we get a “200” response - otherwise error out and let user know the response code
    - Check that we have at least one tag - otherwise error out and let user know about tags

If you wish, you can test this with my fork: drogar/raygun-rails4 - The latest version with kaminari is tagged.