Changed html_use_smartypants to False.

This prevents the html builder from converting "typewriter apostrophes"
(U+0027) to "typographic apostrophes" (U+2019). This was an issue if
somebody copy and pasted the reactions (e.g. vol1' + surf1,) on the
website, since neither CellBlender nor MCell parse U+2019 as if it were
U+0027.