public function findByVisa($visaId)
 {
     $requirements = Requirement::join('visa_requirements', 'requirements.id', '=', 'visa_requirements.requirement_id')->orderBy('title')->where('visa_id', '=', $visaId)->get();
     return \Response::json(array('status' => 'success', 'data' => iterator_to_array($requirements)));
 }