RFR [9] 8179021: Latest bugfixes to WebSocket/HPACK from the sandbox repo

[Pavel Rappo]

Hello,

Please review the following change:

   http://cr.openjdk.java.net/~prappo/8179021/webrev.00/

Along with refactoring this change contains a number of critical fixes for
WebSocket. Critical fixes are applied to Receiver and OpeningHandshake.

Also this change removes 2 convenience methods and 1 constant from WebSocket
interface. Since this interface is a part of incubation feature there shouldn't
be any problem. Those members were initially controversial. 

Thanks,
-Pavel