Fix the feed credentials input dialog not showing
Fix icon not appearing in credentials input dialog

The correct icns is now named vienna-3
Fix username/password issues.

Reverse commit 56f3aae90f and fix detection of feeds using username/password.
See http://forums.cocoaforge.com/viewtopic.php?t=26440&p=137699#p137699 and http://forums.cocoaforge.com/viewtopic.php?f=18&t=25229&p=135848#p135168
Merge pull request #256 from barijaona/bugfixes

Password related bugfixes