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.
Put Code model under PpwmMatcher module

The app will be mounted, so this is done to remove the chance of a
conflict. Plus, it's what should have been done anyway.
Add prefix to table name, for namespacing purposes
Merge pull request #2 from joonty/with_pg

Add postgres, activerecord and a Code model