Resolve "Smiley Feedback on TAs"

Another form of rating for TA has been added, as well as the smileys in the student-to-TA feedback UI. FontAwesome was upgraded from 4.7 to 5.10.1 due to lack of icons in the former version.

Minor change: description for the textual feedback is changed too, the "only teachers can see this" is removed.

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

@@ -334,10 +334,14 @@ public class RequestController {
 	public String feedback(	@AuthenticatedUser User user,
 							@PathVariable("id") Long id,
 							@RequestParam(value = "feedback") String feedback,
+							@RequestParam(value = "rating", defaultValue = "-1") Integer rating,
 							RedirectAttributes redirectAttributes) {
 		Request request = getRequest(id);
 		assert request.getRequestEntity().getId().equals(user.getId());
 		request.setFeedback(feedback);
+		if (rating != -1) {
+			request.setFeedbackRating(rating);
+		}
 		requestRepository.save(request);
 		redirectAttributes.addFlashAttribute("message", "Feedback successfully saved.");
 		return "redirect:/request/" + id;