Currency Conversion (WIP)

This is a continuation of https://github.com/duckduckgo/zeroclickinfo-spice/pull/983.

Checklist:

- [x] Desktop direct-conversion look.

![screen shot 2014-10-14 at 11 17 25 am](https://cloud.githubusercontent.com/assets/81969/4631394/3f01bcdc-53b5-11e4-9a5c-bfecb043cfb2.png)

- [x] Desktop shotgun-conversion look.

![screen shot 2014-10-14 at 11 20 14 am](https://cloud.githubusercontent.com/assets/81969/4631441/a044bf76-53b5-11e4-90fd-2f347eff78b2.png)

- [ ] Mobile direct-conversion look.
- [x] Mobile shotgun-conversion look.
- [ ] Tighten triggering