Regression testing sampling app

This pull request has a new Cascade for sampling data and augments Maestro Cascades to include a `--test` option to perform regression tests. While the tests regression app is not feature complete yet (as specified in #21), this pull requests adds the infrastructure required to run the job.

**Note**: Any Downstream projects need to rename `def jobs =` to `def workflow =`.

While both features will compile and do not break existing functionality, the regression test will not yet run and require some work to finish off.

I won't be working on this for a while, so it is best to get it into the code base now.