Make groups selection for user admin view more usable
Make groups selection for user admin view more usable

Instead of the standard select, use Django's own horizontal select box. It
allows filtering and clearer selection/deselection features.

htem/CATMAID,htem/CATMAID,htem/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID,fzadow/CATMAID,fzadow/CATMAID