In recent (?) ActiveRecord versions, NoDatabaseError only takes one argument

Fixes an exception I was seeing with the recent cardserver changes:
/home/vagrant/.gem/ruby/2.1.2/gems/activerecord-4.1.2/lib/active_record/errors.rb:99:in `initialize': wrong number of arguments (2 for 1) (ArgumentError)
Add test
Merge pull request #3 from Shopify/fix-no-db-error

In recent (?) ActiveRecord versions, NoDatabaseError only takes one arg