RFR [13] 8217429: WebSocket over authenticating proxy fails to send Upgrade headers

[Chris Hegarty]

When tunneling WebSocket over a proxy requiring authentication, the
implementation must ensure that the appropriate Upgrade headers are
not lost after the tunnel has been established. The source changes are
quite straight forward, the remaining bulk of the changes are to address
a deficiency in the testing of proxying and authentication, when
establishing a WebSocket connection.

Webrev:
  http://cr.openjdk.java.net/~chegar/8217429/webrev.01/
Bug:
  https://bugs.openjdk.java.net/browse/JDK-8217429

-Chris