FEATURE: Update `discourse-setup` to prompt for MaxMind account ID (#796)

FEATURE: Update `discourse-setup` to prompt for MaxMind account ID (#796)

In order to download the free MaxMind GeoLite2 databases, an account ID
and license key is required going forward. This commit updates
`discourse-setup` to start prompting the user to provide the MaxMind
Account ID first before asking for the MaxMind license key. If the user
does not provide the Account ID, the script will not prompt for the
license key as we assume the user has opted out.

We are aware that we don't have a reliable way to test for changes to
the `discourse-setup` script but it is what it is at this point in time.
We intend to invest resources in improving things in the future but now
is not the time.