[fix bug 1054956] Refactor Firefox OS Get phone logic to remove JS dependency

Refactored "Get a Phone" logic on `/firefox/os/` and `/firefox/os/devices`, so users with JS disabled will get a full list of available phone partners/links in all countries (instead of just a link to the FAQ page). This should mean we now also have just a single list to maintain (in plain HTML :+1:). This will unblock [bug 1049042](https://bugzilla.mozilla.org/show_bug.cgi?id=1049042).

P.S - I also cleaned up some indentation in `get_devices.less` (adding `?w=1` to the PR URL might make review of this file easier).
I think that is maybe over-engineering things a bit too much, although it's an interesting suggestion. My only hesitation was with relying solely on CSS selector matching, but come to think of it I think using html data attributes could be a more robust solution for what we need here. I'll think it over and update tomorrow. Thanks for the feedback!