Ensure that we are not accidentally burying any integration tests
Remove Minitest 5 + Rails test since the two don't work quite yet
Use Appraisal to run test suites

Appraisal is a much better tool for managing custom Gemfiles. Besides, our
hand-rolled didn't really work 100% to load just the gems that individual test
suites needed -- it was possible, for instance, for the wrong version of
test-unit to be loaded.

Fix running test suites so that you don't have to say `bundle exec`, this just
happens automatically.

Also, refactor some of the integration tests and push the bootstrap stuff into
the integration test helper.
Don't crash if an adapter fails to run its #hook method
Use color and nested formatter when running RSpec 1 tests
Add adapter for Test::Unit 2.0.0 under Ruby 1.9

This is the version of Test::Unit that comes with 1.9/2.0.
Name all of the integration test cases consistently
IntegrationWithRails -> RailsIntegrationTests

The file name didn't match the module name and this bothered me.
Remove the None adapter as it is no longer used
Test that the right adapters are being loaded for different test suites
Test that adapters are loaded correctly for Test::Unit 2 + ActiveSupport