Changes in the "desktop" file to achieve that Krusader can be added to favorites in Gnome Dock

Thanks to Jakkubu (Jakub Buczak) from https://bugs.kde.org/show_bug.cgi?id=390732, Nate Graham, and Florian Müllner.

FIXED: [ 390732 ] Cannot add Krusader to favorites in Gnome Dock
BUG: 390732
Differential Revision: http://phabricator.kde.org/D10746