update urlhelper to use uri constructor instead of string concat
update urlhelper to use uri constructor instead of string concat

congysu/WebApi,yonglehou/WebApi,LianwMS/WebApi,lungisam/WebApi,chimpinano/WebApi,yonglehou/WebApi,chimpinano/WebApi,LianwMS/WebApi,abkmr/WebApi,lewischeng-ms/WebApi,lewischeng-ms/WebApi,lungisam/WebApi,scz2011/WebApi,scz2011/WebApi,abkmr/WebApi,congysu/WebApi