Merge branch 'state_machine'

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.