[PrivacyBadger] Syncing firstRun HTML and CSS across the firefox and chrome repos

[Garrett Robinson]

> Are those files compatible enough that there's a directory we can just forcibly sync over to the Firefox tree?

Unfortunately, doing so is non-trivial since the directory structures are radically different. Everything in the Firefox extension is contained in either data/ or data/skin. The Chrome extension's assets are scattered between adblockplus/chrome/content/ui/, adblockplus/chrome/skin/, and I believe some other locations as well. If we unified/simplified the location of assets in the Chrome extension, then this might be possible. The Firefox arrangement could be changed a little as well. The distinction between data/firstRun.html and data/skin/* doesn't really make sense to me. It would probably be clearer just to put everything in a data/firstrun directory.

I would encourage this consolidation in both repos so we can minimize developer time spent manually sync'ing these assets in the future :)