Replace net id with user id in unenque request.

What does this mr do?

Managers and higher level users were unable to unenqueue students from the queue because in the template the user was giving the netid as a paramter and the controller was expecting the username.

Actions taken to fix bug

The parameter has been changed to the user's id in both places to make it easier to keep everything consistent.

Does this MR meet the acceptance criteria?

• I have added a changelog entry to reflect the significant changes I made and the bug I fixed.
• A test was created to test the bug.
• I have updated the documentation accordingly.
• I adhere to the style guide.

closes #273 (closed)

src/main/java/nl/tudelft/ewi/queue/controller/LabController.java

@@ -238,13 +238,13 @@ public class LabController {
 		return "redirect:/lab/" + id;
 	}
 
-	@RequestMapping(value = "/lab/{id}/unenqueue/{netid}", method = RequestMethod.POST)
+	@RequestMapping(value = "/lab/{id}/unenqueue/{userId}", method = RequestMethod.POST)
 	@PreAuthorize("@permissionService.canUnenqueuOthersFromLab(principal, #id)")
 	public String unenqueueOther(@PathVariable("id") Long id,
-			@PathVariable("netid") String netid) {
+			@PathVariable("userId") Long userId) {
 		Lab lab = labService.getLab(id);
 
-		User user = userRepository.findByUsername(netid);
+		User user = userRepository.findOne(userId);
 
 		Optional<Request> request = lab.getPendingRequest(user);
 		if (lab.getCourse().getHasGroups()) {