May not be testing proxy with SSL enough

[jonathanstowe]

When I was testing fixes for #151 and #152 it looked like with NETWORK_TESTING set AND http_proxy set to an otherwise good proxy the tests that do SSL (t/090-ua-ssl.t and t/100-redirect-ssl.t) fail.

I'm not sure if this is due to the implementation or the proxy I am using, if someone could test with a proxy that is known to work with SSL that would be cool.