public function authentication(Request $request)
 {
     if (!$request->isMethod('post')) {
         exit;
     }
     $email = $request->input('email');
     $senha = $request->input('senha');
     $auth = User::authentication($email, $senha);
     if (count($auth) > 0) {
         $user = $auth[0]->id_usu;
         $this->setSession($user);
         return redirect('/');
     } else {
         //return View('helpers/notifications.error', array("msg"=>"Login inválido"));
         return View('user/auth.invalid', array("msg" => "Login inválido"));
     }
 }