[Jobs] Adds ManageController, Refactors job formular

(references gh-21)
[Core] Improvements

* Improvess Forms/DefaultButtonsFieldset
* Adds ModificationDateAwareEntityInterface
* Improves persistence handling
* Improves menu rendering (layout)

(references gh-21)
[Jobs]: Acl, detail view, save und update of jobs

* Adds ACL checks for job entities (create and edit permissions)
* Adds detail view for jobs (basic at the moment)

(references gh-21)
Merge branch 'feature/Jobs-improvements' into develop