Fix broadcast messages

http://catrobatgw.ist.tugraz.at:8080/job/Catroid-custom-branch-test/1225/
(This testrun is from the previous commit because the last one was just a merge conflict)

The failing assert in BroadcastBricksTest.testBroadcastBricks has nothing to do with the broadcast messages itself. I couldn't find the problem yet, because a single testcase run succeeds (http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/859/testReport/org.catrobat.catroid.uitest.content.brick/BroadcastBricksTest/)