Bug 916151 - home page redesign

Bug 916151: Enable home page template switch with query.

Bug 904696: Update home view to support l10n.
Responsification, refactoring some JS, adding B2 stub
More JS cleanup, finishing B2
Add `has_contribute` to homepage context.
progress on l10n options for news
progress on l10n options for news
Responsive styles for small viewports
Bug 909963 - string fixes: no dot, sentence case heading
Bug 916151 - add GA tracking code
Remove features list from Firefox promo bar
l10n, messaging for specific locales
GA tracking fixes