added built in ShareThis.com support

app/models/blog_post.rb

@@ -31,5 +31,22 @@ class BlogPost < ActiveRecord::Base
       })
     end
   end
+  
+  module ShareThis
+    DEFAULT_KEY = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+    
+    class << self
+      def key
+        RefinerySetting.find_or_set(:share_this_key, BlogPost::ShareThis::DEFAULT_KEY, {
+          :scoping => :blog
+        })
+      end
+      
+      def enabled?
+        key = BlogPost::ShareThis.key
+        key.present? and key != BlogPost::ShareThis::DEFAULT_KEY
+      end
+    end
+  end
 
 end

app/views/blog/posts/show.html.erb

@@ -1,3 +1,12 @@
+<% content_for :head do %>
+  <% if BlogPost::ShareThis.enabled? %>
+    <script type="text/javascript" src="http://w.sharethis.com/button/buttons.js"></script>
+    <script type="text/javascript">
+      stLight.options({publisher:'<%= BlogPost::ShareThis.key %>'});
+    </script>
+  <% end %>
+<% end %>
+
 <% content_for :body_content_title, @blog_post.title %>
 
 <% content_for :body_content_left do %>
@@ -15,6 +24,10 @@
   </p>
   <%= @blog_post.body %>
   
+  <% if BlogPost::ShareThis.enabled? %>
+    <span class="st_sharethis" displayText="ShareThis"></span>
+  <% end %>
+    
   <% if BlogPost.comments_allowed? %>
     <h2><%= t('.comments.title') %></h2>