[BUILD] Exports test dependencies in IntelliJ

Powermock and Junit4 libraries.

Change-Id: Ib19f9a9ce1696c0e3010bf75c5f81bcf56ee4b90
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/2021
Tested-by: Jenkins CI
Reviewed-by: Matthias Bohnstedt <matthias.bohnstedt@gmail.com>
Reviewed-by: Holger Schmeisky <google@schmeisky.com>