Merge branch 'release/4.0' into dev

Conflicts:
	frontend/app/timelines/controllers/timelines-controller.js
	frontend/app/timelines/directives/timeline-container-directive.js
	frontend/app/timelines/directives/timeline-table-container-directive.js
	frontend/app/timelines/directives/timeline-toolbar-directive.js
	frontend/app/timelines/models/planning-element.js
	frontend/app/timelines/services/timeline-loader-service.js
	frontend/app/work_packages/controllers/work-packages-list-controller.js
	frontend/app/work_packages/directives/work-package-details-toolbar-directive.js
	frontend/tests/unit/tests/timelines/controllers/timelines-controller-test.js
	frontend/tests/unit/tests/work_packages/controllers/work-packages-list-controller-test.js