webui: change navigation from RCUE to PatternFly
    
    Mainly html and css changes.
    
    Second level menus are absolutely positioned and so they don't adjust container
    size making other elements to overlap.
    
    side effect partially fixes:
    https://fedorahosted.org/freeipa/ticket/3435
    
    Reviewed-By: Endi Sukma Dewata <edewata@redhat.com>