add HTTP proxy authentication support to EM adapters
add HTTP proxy support for Excon
fix HTTP proxy authentication for Patron
fix HTTP proxy authentication for net-http-persistent

Because net-http-persistent 2.8 doesn't unescape `user/password` values,
we override those accessors on the URI instance to return raw values.

References drbrain/net-http-persistent#48
consistently handle 407 Proxy Authentication Required for HTTPS requests
handle a special-case of connection failed with EM

https://travis-ci.org/lostisland/faraday/jobs/9489250
bump jruby-openssl to fix hang issues

It would hang indefinitely for HTTPS requests from JRuby 1.7.4 on my Mac
have script/server log to stdout when called directly
add integration tests for HTTP proxy support

Spins up a proxy server in a separate process, runs a few requests
through it with each adapter to verify that both proxy support and basic
authentication take effect.
ignore Rubinius crashes

I cannot figure it out; I give up