(Re)enable non-UI tests for build and proposed Gerrit changes

I just noticed that the yangide source tree actually includes x4 test projects, but as of today none of them are currently not run during its build and for proposed Gerrit changes. Having tests but not running them seems a shame! (Perhaps something like YANGIDE-10 would even have been detected by this?)

This bug is to discuss what it would take in particular the existing tests in org.opendaylight.yangide.core.tests and org.opendaylight.yangide.m2e.yang.tests for build and proposed Gerrit changes. (I'll create a separate new bug for two other test bundles which I found.)

I can see that these are commented out in the <modules> of the root pom.xml, but I don't really understand why .. do they not run (anymore?) - need help to get them green?

Or were they perhaps commented out fearing that they will not run on a build server due to UI dependencies? As far as I saw, these two actually do NOT contain UI tests, so should be fine.