feat(engine/bpmn): Add the same behaviour for send task as for service task
- add test case for send task with java delegate

related to CAM-942
Merge branch 'CAM-942-SendTask' of https://github.com/polenz/camunda-bpm-platform into polenz-CAM-942-SendTask
Merge branch 'master' of github.com:camunda/camunda-bpm-platform