Fix test when running under proxy
Throw explict NPE with message if setHeader is called with a null key
Change framed channel to perform all actions in the IO thread

This greatly simplifies the thread safety semantics, and improves
performance in most common cases.
Add support for RST_STREAM
Better close behaviour for the SpdyChannel
Make sure servlet timeout is canceled when context is completed
Don't allow stream creation if the channel is closed
Make sure resumeRead() is a resume and not a wakeup
Eagerly mark SPDY requests as terminated if there is no data
Final SPDY fixes, it now passes the test suite