post replacement: add "Replace Image" dialog to post sidebar.

app/views/posts/partials/show/_options.html.erb

@@ -55,6 +55,8 @@
         <li><%= link_to "Expunge", expunge_moderator_post_post_path(:post_id => post.id), :remote => true, :method => :post, :id => "expunge", :data => {:confirm => "This will permanently delete this post (meaning the file will be deleted). Are you sure you want to delete this post?"} %></li>
       <% end %>
 
+      <li><%= link_to "Replace Image", replace_moderator_post_post_path(:post_id => post.id), :id => "replace-image" %></li>
+
       <li id="mobile-version-list"><%= link_to "Mobile version", mobile_post_path(post) %></li>
     <% end %>
   <% end %>