Switch from using scaffolding extensions to autoforme
Add files to run on the Heroku Cedar stack
Add unicorn to Gemfile
Update README with new demo site and minor fixes
Add description for default rake task
Fix links to edit gift/senders/receivers on main page after update to autoforme
Allow editing receivers/senders for gifts
Add migration to fix typo in earlier migration

I'm not sure why this wasn't caught sooner.  Maybe earlier versions
of PostgreSQL ignored it silently.