`grunt appcache` already calls `fetchdb`
rename `prod.html` to `index.html` for simplicity's sake
add comment to README about removing minified files during development
hardcode /lite/ for deploying darjeeling on Marketplace origin (bug 993730)

Note: when offline, appcache is definitely not working:

  http://cl.ly/image/0w0D1S43233N

And I think it's this Firefox bug:

  https://bugzilla.mozilla.org/show_bug.cgi?id=983871