Fixes #455 - Create Group for test patients

[mholck]

While bundling the test cases it will now check for Patients and create a Group that groups all test patients for a given measure. This is output to the test base directory for the measure along with the test bundles and included in the files.

• Github Issue:
• [ X] I've read the contribution guidelines
• [ X] Code compiles without errors
• [ ] Tests are created / updated
• [ ] Documentation is created / updated

By creating this PR you acknowledge that your contribution will be licensed under Apache 2.0

[JPercival]

Whoops. Automerged in master before it finished building. My bad!