[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).
Indeed, good points! Maybe we can improve on this as time goes on, but at least for now we will just have a single source of data to maintain.