Support updated Flack with new rpc paths.
Support updated Flack with new rpc paths.

Flack wants to talk to the PG Clearinghouse at XML-RPC endpoint with
path "/ch". Allow that in pgch.

tcmitchell/geni-portal,charliemeyer/geni-portal,tcmitchell/geni-portal,tcmitchell/geni-portal,tcmitchell/geni-portal,charliemeyer/geni-portal,charliemeyer/geni-portal,charliemeyer/geni-portal,tcmitchell/geni-portal,charliemeyer/geni-portal