public function registrar(Request $request)
 {
     $data = $request->all();
     $validator = Validator::make($data, ['rif' => 'required|rif|unique:provedores', 'nombre' => 'required|']);
     if ($validator->fails()) {
         return Response()->json(['status' => 'danger', 'menssage' => $validator->errors()->first()]);
     } else {
         Provedore::create(['rif' => $data['rif'], 'nombre' => $data['nombre']]);
         return Response()->json(['status' => 'success', 'menssage' => 'Proveedor registrado']);
     }
 }