This is intended to fix the shortcomings of the library when used behind authenticated proxy server. The support authentication method includes only HTTP BASIC and DIGEST.

The integration test implemented does test proxy connections, however an external proxy server (e.g. Squid) need to be configured to test the proxy authentication as the "InJVM"-proxy server does not support it (maybe consider to replace with LittleProxy).
Merge pull request #215 from michaljemala/auth-proxy

Support for proxy servers requiring authentication