Update zepto in combined.js.

Not sure how this slipped out.
Fix giant avatars and other posts view malstyleage.

I forgot we were adding the "iphone" or "ipad" class to the <body> of the posts
view via JavaScript. It broke when I removed the "detect" module from zepto.js.

Since we were doing quite stupid string interpolation on the posts view HTML
anyway, switch to a mustache template. Apply the correct class there, and load
initial CSS and JavaScript via mustache too.