As an admin I like to have no JUnit JARs included in the WAR

[poikilotherm]

This seems to be related to #2940 and #5071.
For unknown reasons, I seem to have missed proper scoping of the JUnit libs.
Thus they get included in the final WAR.

This most certainly is causing strange (non-fatal) errors in the Glassfish logs, see IRC on 2018-10-16 as #5071 was merged before on 2018-09-27.