[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).
Well, the DOM is now the authoritative source, so I think a DOM query is the correct choice. I definitely wouldn't want to duplicate the data set in a JS object - maintenance would be (even more of) a nightmare.

That being said, having the DOM be the authoritative source for this kind of data is indeed dirty. (It even felt kind of dirty in JS.) A more robust solution would be to store this data in a shared view/helper and send it along to the template. We could then write some Python in the templates to generate a JS object as well as the respective DOM elements. The down side would be not caching/minifying/concatenating that JS object, but it's not really enough JS to matter.

@pmclanahan and/or @jgmize - What do you think?