add categories to forum topics

app/views/forum_topics/_form.html.erb

@@ -2,6 +2,11 @@
   <%= simple_form_for(@forum_topic) do |f| %>
     <%= f.input :title %>
 
+    <div class="input">
+      <label for="forum_topic_category_id">Category</label>
+      <%= forum_topic_category_select("forum_topic", "category_id") %>
+    </div>
+
     <%= f.simple_fields_for :original_post do |pf| %>
       <% if !@forum_topic.new_record? %>
         <%= hidden_field_tag "forum_topic[original_post_attributes][topic_id]", @forum_topic.id %>

app/views/forum_topics/show.html.erb

@@ -7,6 +7,8 @@
       <% end %>
     </h1>
 
+    <p class="info">Posted under <%= link_to @forum_topic.category_name, forum_topics_path(:search => {:category_id => @forum_topic.category_id}) %></p>
+
     <% if @forum_topic.is_locked? %>
       <div class="notice">
         <p>This topic has been locked.</p>