If AWS doesn't work, ask again

[Dylan]

Currently we go through a loop looking for AWS regions that work. If nothing works we currently just fail:

✔︎ Authentication successful, token stored locally (/Users/dylanratcliffe/.overmind/token.json)
FATA No regions specified
                                                  exit status 1
                                                               %

Instead we should either:

• Prompt the user that we couldn't authenticate to AWS
• Let the select something else
• Both?