nghttpx: Fix regression bug that frame with stream_id = 0 not handled
Assert ctx->state >= 0 in huffman decoding
Merge branch 'travis' of https://github.com/alagoutte/nghttp2 into alagoutte-travis
nghttp2_hd: Use single buffer for an name/value pair

Previously we use 2 separate buffer for each name and value.  The
problem is we would waste buffer space for name because it is usually
small.  Also tuning buffer size for each buffer separately is not
elegant and current HTTP server practice is that one buffer for 1
name/value pair.  This commit unifies 2 buffers into 1.