Fixed issue 71, add atom feeds.

The basic building block is here with the feed of the timeline, it is
rather easy to add the feed other elements based on this work. This will
require iterations and polishing.

src/IDF/Review/FileComment.php

@@ -110,4 +110,9 @@ class IDF_Review_FileComment extends Pluf_Model
     {
         return '';
     }
+
+    public function feedFragment($request)
+    {
+        return '';
+    }
 }

src/IDF/Review/Patch.php

@@ -115,4 +115,9 @@ class IDF_Review_Patch extends Pluf_Model
     public function timelineFragment($request)
     {
     }
+
+    public function feedFragment($request)
+    {
+        return '';
+    }
 }