Fixing testcases

Pull Request for the MyProjectActivityTest (Do not merge until all points are fixed):

- [x] Fix testRenameCurrentProjectViaActionBar #390 
Jenkins 10 times MyProjectActivityTest#testRenameCurrentProjectViaActionBar:
http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/740/console

- [ ] Fix testRenameProject + refactoring the renaming methods so that the feature works correctly as defined in #387 

- [ ] testImageCache 

- [ ] Fix for LongClickOnTextInList