Add dynamic list to plugin_config forms
    
    This little javascript allows us to dyamically add form fields in
    the ComplexList and MappingList tables. Makes it much easier to add
    elements to these lists.
    
    Signed-off-by: Simo Sorce <simo@redhat.com>
    Reviewed-by: Patrick Uiterwijk <puiterwijk@redhat.com>