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!)

Added:
Enforce prizes as US only use geocoder gem.  Override "public" geocoder server address to use the faster ".ec1.internal" address on staging and production.
Check for presence of email address before sending prize email messages out - we were seeing instances of SMTP failures in honeybadger because the user had no email address.