perf(router) various improvements
perf(router) various improvements

* use string.find instead of re.find whenever possible when matching URI
prefixes
* use string.sub for prefix URI stripping instead of re.match
* use string.find/string.sub for Host port stripping

icyxp/kong,jebenexer/kong,Kong/kong,Kong/kong,salazar/kong,Mashape/kong,shiprabehera/kong,Kong/kong