e-d-s: When an avatar has been removed, set it to null
e-d-s: When an avatar has been removed, set it to null

Though new_avatar was null, I prefer to even more
obvious about what is going on.

Helps: https://bugzilla.gnome.org/show_bug.cgi?id=655374

GNOME/folks,pwithnall/folks,renatofilho/folks,renatofilho/folks2,renatofilho/folks,pwithnall/folks,renatofilho/folks2,renatofilho/folks,GNOME/folks,pwithnall/folks,GNOME/folks,renatofilho/folks2,renatofilho/folks,renatofilho/folks2