Merge pull request #864 from Arcticwolf/OPENENGSB-3670

[OPENENGSB-3670] fixed the problem with the wrong configuration in the integration tests
[OPENENGSB-3664] implemented context based concurrency management for the persist interface
[OPENENGSB-3664] started writing tests for the new feature
[OPENENGSB-3664] changed the implementation to a better way, added more tests