Running this command for each directory in the `src` folder we generate a
valid `.upgrade.yml` which can be used by other modules that may use this
one as a dependency to upgrade themselves without issue.
Update versions and configurations for tests and code checkers, such as
phpunit and the SilverStripe CI tools. Altered the layout of the
repository to be more in line with other SilverStripe 4 modules (including
core ones).
