Use correct request property to determine remote IP address

Per the documentation (and actual behavior) request.UserHostAddress
returns the DNS/IP of the server. For the IHttpRequest.RemoteIp
property we want the remote client's IP address, and for that we need
to use request.RemoteEndPoint.
Merge pull request #586 from aaronlerch/master

Use request.RemoteEndPoint instead of request.UserHostAddress to supply the value for IHttpRequest.RemoteIp