Handle KDE update test when KDE has aleady found updates
    
    We do the 'desktop update' test for KDE via the notification
    icon thingy, and it behaves differently depending on whether it
    has already detected there are updates or not. The test only
    works at present in the case where it *hasn't* - it expects the
    notification icon to be in the extended panel and it expects to
    see a 'refresh' button, neither of which is the case if it's
    already noticed there are updates to install.
    
    We should also force PackageKit to update its list of available
    updates after we set up our 'special' update, otherwise on this
    path KDE will only install the updates it found *before* we did
    our stuff, and the test will fail as our special update won't be
    there.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>