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

- [x] Fix testRenameProject + refactoring the renaming methods so that the feature works correctly as defined in #387 
Added two asserts, which check wether the current project stays the same
Jenkins 10 times MyProjectActivityTest#testRenameProject
http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/749/console

- [x] Fix testImageCache 
Jenkins 10 times MyProjectActivityTest#testImageCache:
http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/748/console

- [x] Fix for LongClickOnTextInList

Jenkins 10 times MyProjectActivityTest (all green builds):
[Run#1](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/781/console), [Run#2](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/782/console), [Run#3](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/784/console), [Run#4](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/785/console), [Run#5](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/787/console), [Run#6](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/788/console), [Run#7](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/790/console), [Run#8](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/791/console), [Run#9](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/792/console), [Run#10](http://catrobatgw.ist.tugraz.at:8080/job/Catroid-single-UI-test/793/console)