ZipFileStorage: use .push() instead .then() thx @cedric.leninivin

src/jio.storage/zipfilestorage.js

@@ -63,28 +63,25 @@
    * @constructor
    */
   function ZipFileStorage(spec) {
+    var storage = this,
+      zip = new JSZip();
     if (spec.file) {
-      //if (spec.file instanceof Blob) {
-      //  throw new TypeError("ZipFileStorage 'url' is not of type string");
-      //}
-      var storage = this;
       this._unzip_queue = new RSVP.Queue()
         .push(function () {
-          var zip = new JSZip();
           return zip.loadAsync(spec.file, {
             createFolders: true,
             checkCRC32: true
+          });
         })
-            .then(function () {
+        .push(function () {
           storage._zip = zip;
           return zip;
         }, function (error) {
           storage._error = error;
           throw error;
         });
-        });
     } else {
-      this._zip = new JSZip();
+      this._zip = zip;
     }
   }