Change "require_once" to "require" so that filters get applied on multiple application boots during unit tests

I just pulled my hair out for about an hour (hey, it happens) because my unit tests passed in isolation but some failed when run together.

I eventually found that the reason was because the "check-authorization-params" filter was only loaded on the first test and not in the others.

I think it might even be better refactored if the service provider called the 'router' directly to add the filters (instead of loading a file with the Route::filter references). I might try that but for the time being this works just fine :)