* add --dry to bin/setup system:upgrade ; trace patches ; allow MailChecker to fail (when table 'usr' does not exist anymore...)
* MailChecker now works on 'usr' and 'Users' table
* typo
* typo again
* don't create appbox.Registrations if exists
* don't create tables if already exists
* Revert "don't create appbox.Registrations if exists"
This reverts commit 652131aff7.
* drop (empty ?) tables already created before patch
* reorder drop / delete to follow fk rules
* fix typo that makes ApiMigration to run event when table exists ; Move some drop tables at the end
