LPS-38170 fix default area when changing the avatar and don't open it in a browser window

Hey Nate, 

this fixes 2 issues:

1. Before, uploading an image would select just a part of it which was very weird. By default it selects now the whole image but then users can crop it

2. Now instead of opening a new browser window we open a dialog, this will work in tables and mobiles now and it is much nicer to use.