Possible fix for jacoco surefire problem

Workaround for PowerMock / JDK incompatibility seems to have broken the Jacoco reporting of kernel-impl unit tests.  This PR adds some additional Surefire configuration information so that it (in theory) will work with Jacoco.

I think this will fix the problem, but am not running Sonar locally so am hoping Jenkins is run as a result of this PR (so I can see whether it actually fixes the problem or not).