Add rails version Gemfiles and reconfigure travis.yml
Use ActiveSupport::TestCase to support multiple Minitest versions
Use ActiveRecord::TestCase rather than hand-rolled helpers

Since they deprecated external use, just port out of AR to support >=4.1
Simplify database_cleaner usage and bump version
Tests passing on Rails 4.0 and 4.1
Don't shadow ActiveRecord::TestCase, just mixin to ActiveSupport::TestCase
Simplify test directory structure
Merge pull request #12 from kongregate/test-multiple-rails-versions

Test multiple rails versions