修复课程讨论区自己发布的帖子没有编辑功能的问题；

修复课程讨论区回复和编辑帖子内容附件的显示bug

app/views/messages/_course_show.html.erb

@@ -75,14 +75,14 @@
                 l(:button_edit),
                 {:action => 'edit', :id => @topic},
                 :class => 'icon icon-edit'
-        ) if @message.editable_by?(User.current) %>
+        ) if @message.course_editable_by?(User.current) %>
     <%= link_to(
                 l(:button_delete),
                 {:action => 'destroy', :id => @topic},
                 :method => :post,
                 :data => {:confirm => l(:text_are_you_sure)},
                 :class => 'icon icon-del'
-        ) if @message.destroyable_by?(User.current) %>
+        ) if @message.course_destroyable_by?(User.current) %>
   </div>
 
   <div class="lz-left">