Add software version check to test metedata

[nixpanic]

Because tests and code are split over multiple repositories, it would be good to have an option in the test metadata that can be used to only run the test if the version of the components is high enough. (Or run the tests, but do not include the result in the final PASS/FAIL result?)

Practical example: I would like to add a test to distaf that tests for different mount options. The change in Gluster might not be merged or backported to all branches yet. It would be bad for distaf to fail for tests that are not expected to pass for certain versions.