Issue #117 Versioned speech assets

I moved the code to initialize the speech cache, and to create the static
site speech here into the theme. I modified the speech file names, they
no longer include the language. Now static speech assets get versioned like
all the others.
Issue #116, fix gallery index
Issue #96, EPUB.

Now you can download a book in EPUB format. They appear to work on the iPad. They
don't look so good in the Ubuntu e-reader but maybe there is some problem with it?

I have done almost nothing to the style. It will be easy to tweak the stylesheet
in EPub/page.html if needed.
Clean up versioned build.
Clean up debugging.
Move the generated mediaqueries.css into css/ folder.