RFR: 8009251 - Add proxy handling and keep-alive fixes to jsse

[Rob McKenna]

Hi folks,

I'd like to port some changes around proxy handling, keep alive and 
tunnelling to the HttpsClient. These should have been done along with 
the HttpClient. Webrev is at:

http://cr.openjdk.java.net/~robm/8009251/webrev.01/

related issues:

https://jbs.oracle.com/bugs/browse/JDK-7199219
https://jbs.oracle.com/bugs/browse/JDK-7199862

Thanks,

     -Rob