[fix bug 1110848] Remove 'Web We Want' promo from whatsnew/firstrun pages

* Removes conditional "Web We Want" promo from whatsnew/firstrun pages (is currently shown if the user is already signed into Sync).
* Sync promo is now always shown, and links directly to `about:accounts` in Firefox >= 31.
* Sync promo in `firefox/search_tour/tour.html` now also links directly to `about:accounts` for consistency.
* Also removed `australis-page-parallel.less` as this template design is no longer being actively used.

Template can be see on URL's such as `firefox/29.0/whatsnew/?oldversion=33.0` and `firefox/34.0/firstrun/`