#129 desktop file needs changes

[Jakob Haufe]

* Encoding is deprecated as per http://standards.freedesktop.org/desktop-entry-spec/desktop-entry-spec-0.9.5.html#deprecated-items
* Name should only contain "gLabels"
* GenericName should be added, containing "Label Designer"
* Translations need to be changed accordingly
* See http://bugs.debian.org/660642