Merge pull request #15 from emmaattwell/gh-pages

I'm merging this now. I haven't checked all the docs, but we'll have a chance to see if all's well when we output proofs and check web output.
Merge pull request #16 from emmaattwell/gh-pages

Merging 'Changes after copy edit' now, though I haven't checked the files closely, we'll have a chance to check output at proofs/web output.
 Add book YAML headers, regen _site

Also remove .txt duplicate intro