Moved pure persistence test to its own file and made it independent from Activities.
Bugfix: Activity.fillFromUI must not change the ID of the activity.
TestHelper now accepts beans as parameter. This is required for database tests.
Concurrency test and adaption for activities index.
Removed unnecessary line.
Merge pull request #584 from NicoleRauch/master

Versions-Konflikt-Behandlung beim Speichern einer Activity