refactor tests for new emulators

see commit message for detailed information.
most fixes needed for new emulators (api 18), but they also work with our current ones.

testrun with new emulators (master): https://jenkins.catrob.at/view/All-Categories/view/Experimental/job/Catroid-Multi-Job-Custom-Branch-RELOADED/138/
testrun with new emulators (this branch - still some tests failing, but no crashes): https://jenkins.catrob.at/view/All-Categories/view/Experimental/job/Catroid-Multi-Job-Custom-Branch-RELOADED/146/

testrun with old emulators: https://jenkins.catrob.at/job/Catroid-Multi-Job-Custom-Branch/1926/