webui: do not create <hr> delimiter between sections
    
    - section delimiter don't look good and limits UI
    Their removal will allow:
    - section hiding (needed in aci v2 UI)
    - fluid section layout
    
    prerequisite for:
    https://fedorahosted.org/freeipa/ticket/4079
    
    Reviewed-By: Adam Misnyovszki <amisnyov@redhat.com>
    Reviewed-By: Petr Viktorin <pviktori@redhat.com>