CA-293478: Always set the WebRequest properties to the values specified by the JsonRpcClient.
CA-293478: Always set the WebRequest properties to the values specified by the JsonRpcClient.

This fixes issue where the WebRequest.Proxy had a non-null default value, which
prevented connection to a server with the management interface on a vlan.

Signed-off-by: Konstantina Chremmou <a7d1f757a659045fb6db8c1e3849a1c8ad00b97a@citrix.com>

kc284/xen-api-sdk,kc284/xen-api-sdk,xapi-project/xen-api-sdk,xapi-project/xen-api-sdk,kc284/xen-api-sdk,xapi-project/xen-api-sdk,kc284/xen-api-sdk,xapi-project/xen-api-sdk,xapi-project/xen-api-sdk,kc284/xen-api-sdk,kc284/xen-api-sdk,xapi-project/xen-api-sdk