Add Spice phone to Fx OS pages. Bug 1056903.

- Add Tamil screenshots to /firefox/os/.
- Improve selector used for en-US/India content on /firefox/os/.
- Switch HTML comments to Jinja comments on devices page.
Merge pull request #49 from mozilla/bug-1056903-fxos-spice-device

Add Spice phone to Fx OS pages. Bug 1056903.