Use OHDSI Rabit in a Hat tool for unit testing

[vojtechhuser]

example unit test for HCUP https://github.com/OHDSI/JCdmBuilder/blob/master/tests/HCUPETLToV5/HcupTests.R

Documentation: http://ohdsi.github.io/WhiteRabbit/riah_test_framework.html

This framework does not test whole set of data but simply picks one row in source and specifies how it should appear in target. It is also organized by OMOP table.