Add more detail to setup in README
Add activerecord and postgres adapter gems
Add Rakefile with activerecord rake tasks
Add rake to Gemfile
Add database config file and load active record

Also create the first migration, to add a Code model.
Merge branch 'readme-update'
Create User model and add paired_code_id to Code

Also add method for generating a code string, and for creating a pair of
linked codes.
Add temporary action to create two linked code pairs
Working flow of user logging in and submitting code

This now uses ActiveRecord models and relationships to link codes and
users.