Fix some errors and warnings

* uninitialized constant BusinessUnitsHelper (NameError)
* superclass mismatch for class Mysql2Adapter (TypeError)
* Passing a template handler in the template name is deprecated. ...
Fix failing speFix failing specc

Error was

> ActiveRecord::DeleteRestrictionError:
>       Cannot delete record because of dependent purchases

Remove the block and depend in DatabaseCleaner to clean the database properly.