Set profile/avatar option hidden when using Prosody
Gajim behaves incorrectly in the way it determines whether a server supports vcards. Instead of using disco, it fires a vcard request during login.
If the response to the vcard request is type='error' then line ~1134 of connection_handlers.py is hit, which sets self.vcard_supported = False.
The problem is that if you have no vcard, you will get an error when you request it, as the XEP states should happen: http://www.xmpp.org/extensions/xep-0054.html#example-3
The result is that Gajim won't let Prosody users set a new vcard, but will let them modify it if they already have one (because there was no error returned by the initial vcard request).
Gajim should detect support as per the XEP: http://xmpp.org/extensions/xep-0054.html#support
Secondly (and less importantly) requesting the vcard during login should be avoided if possible (for faster logins), otherwise we will need to implement vcard versioning ;)