public function postAddTask()
 {
     // validate
     $validator = Taskcard::validate(Input::all());
     if ($validator->fails()) {
         return Response::json($validator->messages());
     }
     $task = new Taskcard();
     $user_id = Auth::user()->id;
     $task->title = Input::get('title');
     $task->content = Input::get('content');
     if (!is_null(Input::get('status'))) {
         $task->status = Input::get('status');
     } else {
         $task->status = "Todo";
     }
     if (!is_null(Input::get('start'))) {
         $task->start = Input::get('start');
     }
     if (!is_null(Input::get('end'))) {
         $task->end = Input::get('end');
     }
     if (strtotime($task->start) >= strtotime($task->end)) {
         return Response::json(array('error' => 'Invalid time'));
     }
     $task->save();
     return Response::json(array($task));
 }