issue#8 Create new Task entity based on our disscussing and refactor the old

The refactoring introduced the following changes:

issue#8 Refactoring service.xml
- service.xml - modified

issue#8 Extending Impl classes and adding TaskSessionFinderImpl with default.xml
- TaskLocalServiceImpl - modified
- TaskSessionLocalServiceImpl - modified
- TaskSessionImpl - modified
- TaskSessionFinderImpl - added
- default.xml - added
- ... build-service was executed to regenerate the services.

issue#8 Adjusting view.xhtml and TaskBean to the refactored services
- view.xhtml - modified
- TaskBean.xml - modified