scale height of info box on mobile

Info boxes default to a minimum height of 240px. This allows for
consistent readability if the page is full-width and the text doesn't
aggressively wrap.

When necessary, allow height to scale to fully display all of the
written content. This could potentially cause the two boxes to scale to
different heights. However, on smaller screens, the boxes will already
move to stack on top of each other, so this difference won't be
noticeable.
remove unused code-prettify JS
use a script loader to manage dependencies

With a script loader, we have better control over when different scripts
can execute. Specifically: we need to wait until the betterlink source
loads before calling init(), and we don't need google-code-prettify to
block anything else. Also gets rid of the ad hoc checking to see if
betterlink has loaded (ignorant of whether it has finished executing).
add back international content on homepage

previous blocker: loading betterlink-bespoke.js with options had race
condition issues (solved via a script loader here and with changes to
the source file).