If you're trying to use `brew info --json=v2` to get an installed
version and figure out if it is outdated: you're going to have a bad
time with `auto_updates` casks because `installed_version` alone is not
enough to get the actually currently installed version of the app.
Instead, in these cases, try to read from `Info.plist` if there is one
and use that version.
While we're here, add a `blank?` method to `Version` so we can use it
for `present?` checks (making a `null?` `Version` object `blank?`).
Co-authored-by: Markus Reiter <me@reitermark.us>
03e583e746