Update p_auth_configure_challenge_handler.md
Update p_auth_configure_challenge_handler.md

Added note regarding the new http.proxy service (#357)
cmebarrow/gateway,irina-mitrea-luxoft/gateway,michaelcretzman/gateway,sanjay-saxena/gateway,stanculescu/gateway,a-zuckut/gateway,DoruM/gateway,biddyweb/gateway,justinma246/gateway,mjolie/gateway,irina-mitrea-luxoft/gateway,mgherghe/gateway,adrian-galbenus/gateway,jfallows/gateway,mgherghe/gateway,dpwspoon/gateway,michaelcretzman/gateway,vmaraloiu/gateway,danibusu/gateway,dpwspoon/gateway,DoruM/gateway,a-zuckut/gateway,AdrianCozma/gateway,kaazing/gateway,jitsni/gateway,danibusu/gateway,mgherghe/gateway,adrian-galbenus/gateway,a-zuckut/gateway,cmebarrow/gateway,chao-sun-kaazing/gateway,dpwspoon/gateway,dpwspoon/gateway,chao-sun-kaazing/gateway,jfallows/gateway,cmebarrow/gateway,jfallows/gateway,kaazing/gateway,michaelcretzman/gateway,sanjay-saxena/gateway,nemigaservices/gateway,nemigaservices/gateway,cmebarrow/gateway,a-zuckut/gateway,stanculescu/gateway,Anisotrop/gateway,sanjay-saxena/gateway,chao-sun-kaazing/gateway,Anisotrop/gateway,stanculescu/gateway,kaazing/gateway,vmaraloiu/gateway,stanculescu/gateway,kaazing/gateway,biddyweb/gateway,jfallows/gateway,irina-mitrea-luxoft/gateway,danibusu/gateway,veschup/gateway,justinma246/gateway,jitsni/gateway,mgherghe/gateway,michaelcretzman/gateway,adrian-galbenus/gateway,vmaraloiu/gateway,Anisotrop/gateway,danibusu/gateway,nemigaservices/gateway,sanjay-saxena/gateway,justinma246/gateway,biddyweb/gateway,AdrianCozma/gateway,vmaraloiu/gateway,chao-sun-kaazing/gateway,mjolie/gateway,veschup/gateway,biddyweb/gateway,mjolie/gateway,mjolie/gateway,AdrianCozma/gateway,DoruM/gateway,jitsni/gateway,AdrianCozma/gateway,Anisotrop/gateway,nemigaservices/gateway,jitsni/gateway,adrian-galbenus/gateway,justinma246/gateway,irina-mitrea-luxoft/gateway,veschup/gateway,veschup/gateway,DoruM/gateway