Add mtime to static resource URLs.
Add mtime to static resource URLs.

We need clients to always use the newest JavaScript. Auto-versioning all
static resources means that a new version will always have a different URL,
so the user doesn't have to press Refresh to receive it. It also makes it
possible to use a large max-age and eliminate useless 304 responses.

fmfi-svt/votr,fmfi-svt/votr