Option to create empty program

fixes #497

Jenkins testruns
[Catroid-custom-branch-no-emma-test #74](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-custom-branch-no-emma-test/74/)
[Catroid-single-UI-test #900 (NewProjectDialogTest)](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/900/)