Fix for PDF leaderboard files

PDF files cannot be displayed in an `<img>` tag, we should be using the pre-made template.
Also moving the image below the response because it looked weird above. Tests updated.

openassessment/templates/openassessmentblock/leaderboard/oa_leaderboard_show.html

@@ -17,11 +17,9 @@
                             </h4>
                             {% endwith %}
                             <div class="leaderboard__answer">
-                                {% if topscore.file %}
-                                <img class="leaderboard__score__image" alt="{% trans "The image associated with your peer's submission." %}" src="{{ topscore.file }}" />
-                                {% endif %}
                                 {% trans "Your peer's response to the question above:" as translated_label %}
                                 {% include "openassessmentblock/oa_submission_answer.html" with answer=topscore.submission.answer answer_text_label=translated_label %}
+                                {% include "openassessmentblock/oa_uploaded_file.html" with file_upload_type=file_upload_type file_url=topscore.file class_prefix="submission__answer"%}
                             </div>
                         </li>
                     {% endfor %}

openassessment/xblock/leaderboard_mixin.py

@@ -86,7 +86,7 @@ class LeaderboardMixin(object):
 
             score.pop('content', None)
 
-        context = {'topscores': scores, 'allow_latex': self.allow_latex,}
+        context = {'topscores': scores, 'allow_latex': self.allow_latex, 'file_upload_type': self.file_upload_type,}
 
         return 'openassessmentblock/leaderboard/oa_leaderboard_show.html', context
 

openassessment/xblock/test/test_leaderboard.py

@@ -242,6 +242,7 @@ class TestLeaderboardRender(XBlockHandlerTransactionTestCase):
             {
                 'topscores': scores,
                 'allow_latex': xblock.allow_latex,
+                'file_upload_type': xblock.file_upload_type,
             },
             workflow_status='done'
         )