Ensured Netty provider uses CONNECT when proxying ws

The WS standard requires that clients use the CONNECT method when proxying WebSockets, even if they aren't using SSL.  The Grizzly provider already supported this, but the Netty didn't.

I also implemented a test that tested this case.

I've made this change and PR against the 1.8.x branch, master is significantly different but briefly reading the code it looks like the bug is there as well.  If you'd prefer it against master first, and then backported, or want me to submit another PR against master/1.9.x, let me know.