changed activatable model to require a field definition of which field is activatable
updated the rest of the model manager methods to deal with the custom field
bumped the version
added docs and tests for new functionality
added release notes
Merge pull request #5 from wesleykendall/develop

Added configurable is_active field to Activatable Models
Merge pull request #6 from ambitioninc/develop

Added configurable is_active field to Activatable Models