Upgrading to HTTP/2 draft 14 HTTP/1.x message flow

Motivation:

HTTP/2 draft 14 came out a couple of weeks ago and we need to keep up
with the spec.

Modifications:

-Allow informational type messages to be sent up the pipeline immediatley.
-Corrections to HttpObject comparitors to support test cases
-New test cases to support sending headers immediatley
-Bug fixes cleaned up to ensure the message flow is terminated properly

Result:
Netty HTTP/2 to HTTP/1.x translation layer will support the HTTP/2 draft message flow.
Good point the comment and link to the spec are not clear (and still refer to outdated Http2HttpMessageAccumulator).  The original intention (before I discovered that this method is only called when END_HEADERS has been read) is no longer a legitimate concern.  However, the logic may make sense still....if it is an error to receive a push promise for a stream that is already opened.  I think it is an error because I don't see the promise being received after the idle state (http://tools.ietf.org/html/draft-ietf-httpbis-http2-14#section-5.1.)

Either way I will update the comment.