Rename RemoteAddress::getOne to getClientAddress
“get one” asks a second question: “which one?”
The answer is the first one, ie “the client IP”, per future RFC 7239.
This is a follow-up for change b7683f8d6cf8.
Test Plan: Run tests to ensure it's correctly renamed everywhere
Reviewed By: dereckson
Differential Revision: https://devcentral.nasqueron.org/D1625