Create 2 new dialog controllers

Image import is now triggering a popup after selecting the file.
Same for local saves.

Drag and drop of .piskel files opens the piskel immediately !

Remains to do :
- redesign the dialog for import image and browse local
- create dialog for recover session
- improve recover session to handle more than the last session

src/js/utils/DateUtils.js

@@ -11,6 +11,7 @@
 
   ns.DateUtils = {
     format : function (date, format) {
+      date = new Date(date);
       return pskl.utils.Template.replace(format, {
         Y : date.getFullYear(),
         M : pad(date.getMonth() + 1),

src/js/utils/PiskelFileUtils.js

@@ -0,0 +1,17 @@
+(function () {
+  var ns = $.namespace('pskl.utils');
+
+  ns.PiskelFileUtils = {
+    loadFromFile : function (file, onSuccess, onError) {
+      pskl.utils.FileUtils.readFile(file, function (content) {
+        var rawPiskel = window.atob(content.replace('data:;base64,',''));
+        var serializedPiskel = JSON.parse(rawPiskel);
+        var fps = serializedPiskel.piskel.fps;
+        var descriptor = new pskl.model.piskel.Descriptor(serializedPiskel.piskel.name, serializedPiskel.piskel.description, true);
+        pskl.utils.serialization.Deserializer.deserialize(serializedPiskel, function (piskel) {
+          onSuccess(piskel, descriptor, fps);
+        });
+      });
+    }
+  };
+})();