HTTP proxy: use 3128 for HTTP and 3129 for HTTPS
HTTP proxy: use 3128 for HTTP and 3129 for HTTPS

Since the system can have different proxies for HTTP and HTTPS, we
should separate the traffic by using two different ports. We can then
use the HTTP proxy setting for the HTTP traffic and the HTTPS proxy
setting for the HTTPS traffic.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@docker.com>

djs55/vpnkit,djs55/vpnkit,djs55/vpnkit