Adjust timer to refresh ovirt foreign menu
    
    This is a temporary solution, as discussed in the bug. We will adjust
    the timer to refresh the ISO list from 15 seconds to 5 minutes (300
    seconds), while reworking in the UI to replace the menu with a dialog,
    which seems a saner way to display the list.
    
    Resolves: rhbz#1347726
    
    Signed-off-by: Eduardo Lima (Etrunko) <etrunko@redhat.com>