Version 0.1.7

• Removed the methods old_interactor, old_command, and old_query from both Pavlov module and Helpers.
• In preparation for changes to the validation system, we've changed the name of the method you should implement that performs the validations. This was valid?, and it is now validate. Like execute, this method should not be called directly, instead Pavlov provides a wrapper method called valid?. This allows us to add default validations without you having to remember to call super.