Add support for common rules across types

Add support for common rules across types

Refactor the Rule Driven Validator implementation for loading the Groovy
rules. Firstly, support multiple top-level folders. Secondly, include
each top-level folder in the set of paths to search for *.groovy files.

Pull a common rule up to the top-level to remove the duplication.

Add tests to exercise the exception handling code.

Change-Id: Ib70fe03ab5b1f2f8c1711760236b07850aaaa398
Issue-ID: AAI-2155
Signed-off-by: mark.j.leonard <mark.j.leonard@gmail.com>