Add in StoryManager, 3 assets for managing news content in WebGUI.

Several small API changes to Keyword and AssetExportHtml to support StoryManager functionality.

t/lib/WebGUI/Test.pm

@@ -370,6 +370,20 @@ sub session {
     return $SESSION;
 }
 
+#----------------------------------------------------------------------------
+
+=head2 webguiBirthday ( )
+
+This constant is used in several tests, so it's reproduced here so it can
+be found easy.  This is the epoch date when WebGUI was released.
+
+=cut
+
+sub webguiBirthday {
+    return 997966800 ;
+}
+
+
 
 #----------------------------------------------------------------------------