Remove obsolote ITMS_HANDLER reference in desktop file
Ever since commit 62138516 the "@ITMS_HANDLER@" in the file never gets substituted, thus creating a broken desktop file. (Noticed this when doing a "update-desktop-database" on my system.
Error in file "/usr/share/applications/rhythmbox.desktop": "@ITMS_HANDLER@" is an invalid MIME type ("@ITMS_HANDLER@" does not contain a subtype)