Database migrations + activerecord

Pakket will throw an error if you haven't configured a database. How do we deal with this, should there be an option to use a database or something?

**Sample migration usage**

`php vendor/bin/phinx init`
`php vendor/bin/phinx create AddUserTable`
`php vendor/bin/phinx migrate -e development`

**Sample activerecord model**

`app/models/User.php`

**Known code violations**
  * `app/models/User.php` needs class refactoring to use proper psr-4. I'm not too familiar with this yet.

**Known limitations**
  * The adapter between Phinx and ActiveRecord supports MySQL only at the moment. (config/database.php)
  * The adapter only supports the default Phinx environments at the moment: production/testing/development, custom environments will not work
Idea: We could make some facade classes in core for stuff like this, so it just looks like `extends PakketModel` or some cool name