refactoring(engine-cdi): Rename task form bean

- rename taskForm bean from 'camunda.taskForm' to 'camundaTaskForm' to fix
  IBM Websphere problems
- 'camunda.taskForm' bean exists only for compatibility like 'fox.taskForm'
- adjust testcase

related to #CAM-1698
Merge branch 'master' of github.com:camunda/camunda-bpm-platform