Makes adapter inclusion self-contained.
Adds workflow_adapter hook support.
Merge pull request #111 from damncabbage/adapters-for_upstream

Adds ability to select different adapters via a `workflow_adapter` class method.
Changelog note for 111
• Adds without_*_state scope
• Adds 'not_*?' methods to models
Update README.markdown
Merge branch 'master' of github.com:TwilightCoders/workflow