Merge branch 'lab-intervals' into 'development'

...n/java/nl/tudelft/ewi/queue/controller/LabController.java

.../nl/tudelft/ewi/queue/exception/InvalidSlotException.java

src/main/java/nl/tudelft/ewi/queue/model/Lab.java

src/main/java/nl/tudelft/ewi/queue/model/Request.java

src/main/java/nl/tudelft/ewi/queue/service/LabService.java

src/main/java/nl/tudelft/ewi/queue/tasks/RequestTasks.java

src/main/resources/templates/course/view/assignments.html

src/main/resources/templates/lab/create.html

src/main/resources/templates/lab/edit.html

src/main/resources/templates/lab/enqueue.html