Fixed bug displaying incorrect links in preferences

Closes #786 (closed)

app/views/admin/course_editions/preferences/show.html.erb

@@ -73,7 +73,7 @@
             <ul id="student-list">
               <% @student_preferences.each do |preference| %>
                 <li>
-                  <a href="<%= admin_user_path(@user) %>">
+                  <a href="<%= admin_user_path(preference.student) %>">
                     <%= preference.student.display_name %> (<%= preference.student.email %>)
                   </a>
                 </li>