haproxy-devel added widget from external github tree made by: jvorhees

haproxy-devel added widget from external github tree made by: jvorhees
-widget, source: https://github.com/jvorhees/pfsense/tree/master/Widgets/Haproxy
-widget, dropped socat requirement
-widget, improved enabling/disabling server abilities
-support configuration of transparent proxying (though currently disabled)
-fix for default http check
-better startup error checks