Refactor SetSizeToBrickTest and testRestartProjectWithSound

10 iterations SetSizeToBrickTest:
http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/468/
5 iterations StageDialogTest (including the testRestartProjectWithSound):
http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/473/

Currently running Custom Branch Test:
http://catrobatgw.ist.tugraz.at:8080/job/Catroid-custom-branch-test/706/