BTTF: Coupon mountain design cleanup

//cc @russellholt @jagtalon @jdorweiler 

I've cleaned up CouponMountain a little more:
- Switched to shorter titles (from the API) for the tiles and I now show the expiry date when present in the detail view (I also strip any wording about expiry from the detail-view heading)
- Made the coupon text a little larger (it was quite small before)
- Added default alphabetical sorting
- Removed the old unneeded detail template