TESTS: Add unit test for installed software

[HenrikBengtsson]

Add make validate that runs rudimentary unit tests that the installed software and module works as expected, e.g.

• [x] BUILT-IN: assert that module can be loaded and unloaded
• [x] BUILT-IN: assert that binaries can be found
• [x] PER TOOL: assert that binaries can be called, e.g. --version and --help
• [ ] PER TOOL: assert that man pages can be found (moved to #83)
• ...

Use bats-core for this. I can imagine we'll end up adding a subfolder tests/ to each software for this.

Open question: How to handle the case when we need different tests for different versions? Can this be dealt with using conditional calls, e.g. if-then?

[HenrikBengtsson]

make, i.e. make all now includes new make check, which runs some basic, built-in load-unload tests for all software tools. One can then add additional tests/*.bats test scripts to any software tool, e.g. https://github.com/HenrikBengtsson/CBI-software/tree/master/CBI/bat/tests