Avatar cannot be cleared
Bug description
I signed into jabber account at home using Adium and it assigned a general avatar to my jabber.org account. When I signed out from Adium, the avatar stayed as part of my jabber.org profile. Then I signed into Gajim at different computer (Win7) and I could not clear the avatar picture. Clicking on "Edit" > "Profile, Avatar", then right-clicking on avatar and choosing "Clear" and pressing "OK" doesn't do the trick. If I go to the "Personal Information" window I see the same picture present. Other people don't see a change in my account either. There have to be a way to clear the avatar, not just replace it with a different picture.
Steps to reproduce
Select an avatar on one computer, Log off/disable jabber account on that computer, Log in to Gajim with the same account on different computer, Go to Edit > Profile, Avatar, Right-click on avatar picture and select Clear, Press OK, Go to Edit > Profile, Avatar, The avatar picture is still there.
Software versions
OS version: Windows 7
GTK version: 2.22.1
PyGTK version: 2.22.0