Show list of feedback messages for specific exercises

app/views/exercises/feedback.html.slim

@@ -0,0 +1,15 @@
+h1 = @exercise
+
+ul.list-unstyled.panel-group#files
+  - @feedbacks.each do |feedback|
+    li.panel.panel-default
+      .panel-heading role="tab" id="heading"
+        div.clearfix
+          span = feedback.user.name
+      .panel-collapse role="tabpanel"
+        .panel-body.feedback
+          .text = feedback.feedback_text
+          .difficulty = "#{t('user_exercise_feedback.difficulty')} #{feedback.difficulty}" if feedback.difficulty
+          .worktime = "#{t('user_exercise_feedback.working_time')} #{feedback.user_estimated_worktime}" if feedback.user_estimated_worktime
+
+= render('shared/pagination', collection: @feedbacks)