add country field.

The puzzle `26-39e9513c` from #26 has to be resolved:

https://github.com/ammaratef45/Attendance/blob/eca2402ae6ed995f3e2a51ecbbc94e2b448d44e6/attendance/lib/ProfilePage/profile_page_viewmodel.dart#L6-L6

The puzzle was created by Ammar Atef on 13-Apr-19.

If you have any technical questions, don't ask me, submit new tickets instead. The task will be \"done\" when the problem is fixed and the text of the puzzle is _removed_ from the source code. Here is more about [PDD](http://www.yegor256.com/2009/03/04/pdd.html) and [about me](http://www.yegor256.com/2017/04/05/pdd-in-action.html).