1065 super avatar

Problem description
===================

We need to remove IOSUsers.getSuperAvatar and Avatar.getCopy() since that API is broken.

Changes description
===================

getSuperAvatar(from=avatar) was removed together with Avatar.getCopy().
That code was very ugly ... especialy the getCopy part.

This is a old tech dept and it was also blocking the upgrade to Python 2.7

I tried to provide a dedicate SuperAvatar .

The implementation of SuperAvatar on Windows is not correct... but since there is no such thing as "root" account on windows, I don't know how to do it better.


How to try and test the changes
===============================

reviewers @alibotean 

Nothing special here. Just run the tests.

Let me know if you smell anything fishy here :)