fix : reduce piskel model size

+ moved Serializer and Deserializer to utils.serialization package
+ put all backward code in utils.serialization.backward
+ added static method on Deserializer to make its usage similar to other
  utils in the package
- still not happy with the names used in Deserializer classes
  (deserializer.deserialize ...)

js/service/LocalStorageService.js

@@ -45,10 +45,9 @@
    */
   ns.LocalStorageService.prototype.restoreFromLocalStorage_ = function() {
     var framesheet = JSON.parse(window.localStorage.snapShot);
-    var deserializer = new pskl.utils.Deserializer(framesheet, function (piskel) {
+    pskl.utils.serialization.Deserializer.deserialize(framesheet, function (piskel) {
       pskl.app.piskelController.setPiskel(piskel);
     });
-    deserializer.deserialize();
   };
 
   /**