proposed re-write of http binding

I took the AI[1] to draft a more formal/rigorous approach to the HTTP binding
section (section 6) before today's WG meeting. Please see attached. It isn't
quite complete, but rather than delay discussion, I am posting this as a WIP
draft as I believe that it reflects my thinking as to the direction that
we should take with regards to transport binding definitions.

Note that this draft reflects my thoughts and not necessarily those
of the WG as a whole. This document is for discussion purposes only
at this time.

Comments welcomed.

Cheers,

Chris

[1] http://www.w3.org/2000/xp/Group/1/07/13-binding-minutes.html