test HTTPS over a proxy

so far, the test will probably fails. We need to find a workaround
for Client.pm.

http://www.perlmonks.org/?node_id=1028125
https://rt.cpan.org/Public/Bug/Display.html?id=1894

see: #1940

Reported-by: Laurent Gachon <laurent.gachon@upmf-grenoble.fr>