Last submitted hours and feedback changes

Multiple cards:

• https://trello.com/c/FwQnhJOG/153-on-lastimportedhoursandfeedbacks-move-the-green-button-including-the-text-ich-bestätige-to-the-bottom-of-the-page
• https://trello.com/c/glT0k8xJ/149-on-lastsubmittedhoursandfeedback-the-field-bemerkungen-on-the-feedback-form-should-not-be-mandatory