cache_classes should be true by default

Rails is assuming a "development mode"-like behavior. It seems that this is actually the exception -- ie not more than a "goodie" for developing.

This should not affect anybody in a bad way. Worst case scenario is that this will actually fix things on misconfigured servers (or in cases where you define your custom environment but don't have a config/environments/custom.rb -- by default Rails should assume that is not another development environment).