Stop Decoding Values

[dstufft]

Currently http-parser converts certain values to str on Python3 instead of leaving them as bytes. This allows treating things which are pure ASCII as strings, however in order to do anything more complex than that is requires an encoding dance to go back to bytes by encoding with latin1 again, and then potentially decoding them again with a different encoding. It would be nice if http-parser at least allowed disabling the decoding if not just stopped doing it altogether.

[benoitc]

should probably only decoded to latin1 if needed... not sure about keeping them as bytes though