Replace JAccept in all Bitrepository implementations

JAccept is an acceptance test framework, made by a former employee, that is no longer maintained (or at least not currently maintained). While it provides fairly useful test reports when building projects, it seems misused in that all our tests make use of it - both in the reference code and in SBpillar. The framework is also not very transparent in how it overtakes the output of running TestNG @Test-annotated methods, making it unintuitive for new developers. In general it just seems that sticking to using industry-standard testing-frameworks would be a much wiser alternative.

As our newer projects at KB all use JUnit for testing, this would be an obvious candidate for replacement. However, there still remains the question of what to do about actual acceptance tests - are they even neccessary? I (rbkr) have looked a bit into JGiven, which seems to work similarly to JAccept in that reports are generated through test scenarios written in plain java, but this framework sees much wider usage.