Fixed custom route for upgrade.
Made standard the config form.
Set InnoDB as default engine.
Allowed admins to change the config of the plugin (same as old UI).
Renamed 'contributed_file' to 'file' in order to use default upload method.
Allowed contributors to edit their contributions.
Simplified contribution controller for contribution.
Fixed link to contribution delete.
Replaced the makeNotPublic() method by the afterSave() hook.