Update requirements document

I've updated our requirements document based on our discussions at the face-to-face and included it as an attachment.  I haven't yet incorporated feedback from the email list post-F2F as consensus in the email thread is not always as easy to tell, and I'd rather wait and cover things quickly in the call before updating the document.

I've added a new section 4 to cover "first pass" requirements rather than trying to edit in place in section 3.  I haven't organized section 4, as I want to wait until we get them all.  As I fill out section 4 I'm striking through the requirements from section 3 that we've dealt with so we can both see we've dealt with them but also still see the text involved.