Uri: fix handling of IPv6 address in HTTP_HOST
Uri: fix handling of IPv6 address in HTTP_HOST

if an IPv6 address is given in HTTP_HOST, do not split
on the first colon to prevent truncating the IPv6 address.

refs #1325

Sam-Burns/Slim,iinux/Slim,designermonkey/Slim,iinux/Slim,mnapoli/Slim,akrabat/Slim,RealSelf/Slim,dopesong/Slim,juliangut/Slim,foxyantho/Slim,iinux/Slim,feryardiant/slim,JoeBengalen/Slim,AndrewCarterUK/Slim,slimphp/Slim