Updated the descriptions of some frames.
Some updates on frame description.
Merge branch 'frames' of https://github.com/hruellan/http2-spec into frames

Conflicts:
	draft-ietf-httpbis-http2.xml
Corrected description of GOAWAY. Updated description of WINDOW_UPDATE
Updated the descriptions of some frames.
Some updates on frame description.
Corrected description of GOAWAY. Updated description of WINDOW_UPDATE
Did a rebase.
Merge branch 'frames' of https://github.com/hruellan/http2-spec into frames
Merge pull request #56 from hruellan/frames

Corrected description of GOAWAY. Updated description of WINDOW_UPDATE.