Some big changes:
* Added some redundant requires so active_support/inflecto can be loaded
without the rest of ActiveSupport.
* Disabled callbacks and validations until they are added and tested.
* Converted specs back to tests, using ActiveSupport::TestCase and the new
#test helper.
* As an experiment, I imported Scott Barron's awesome AASM gem into
ActiveModel. I added multiple state machine support and vastly improved
the API (no more aasm_* prefixes). All the old tests pass. If this bothers
people, I have no problems removing this and contributing the changes back to
AASM. I just feel like AMo is a better spot for all these 'modelish' features.