Prize changes

Near final prize UX

Updated images (thanks, Ross!)
Updated terms&conditions text.  This is stored in a config YML file loaded at startup.  Not localized.
Removed the respond_to & format from the claim_prize method (previous PR feedback)
Rearranged redeem_prizes page per feedback from Hadi.  Text changes from Hadi.
E-mail messages updated to indicate that prizes will be available next week (people are actually receiving these mail messages today!)