public function addInventory($id)
 {
     if (!Sentry::getUser()) {
         return Redirect::route('sessions.create');
     }
     $validator = Validator::make($data = Input::all(), InvoiceLine::$rules);
     if ($validator->fails()) {
         return Redirect::back()->withErrors($validator)->withInput();
     }
     if ($data['quantity'] > Equipment::where('id', '=', $data['item_id'])->first()->quantity) {
         return Redirect::back();
     }
     $data['type'] = 0;
     $data['invoice_id'] = $id;
     InvoiceLine::create($data);
     return Redirect::route('finances.index');
 }