Bug 1010596 fxos devices zte openc

Still waiting on some confirmation in the bug, so not quite ready for review.

* Adds eBay CTA links to the `firefox/os/devices` page for Germany, Russia, United States and United Kingdom.

* Because these phones are aimed more at developers, we only want to show them on the `os/devices` page, and not on `firefox/os`. To do this we've added a `developer_only` property to the partner data that both pages share. The `firefox/os` page will not show a link for a given provider if this property is present.

Apologizes for the massive diff in `firefox-os.js`, 99% of this is just indentation changes. The only real change is [this line](https://github.com/mozilla/bedrock/compare/bug-1010596-fxos-devices-zte-openc?expand=1#diff-829159f527bc87788df23a0863b651f3R27).