ZipFileStorage: use minimified version jszip

Gruntfile.js

@@ -150,7 +150,7 @@ module.exports = function (grunt) {
           'lib/uri/URI.js',
           'node_modules/uritemplate/bin/uritemplate.js',
           'node_modules/lz-string/libs/lz-string.js',
-          'node_modules/jszip/dist/jszip.js',
+          'node_modules/jszip/dist/jszip.min.js',
 //           'node_modules/moment/moment.js',
           'lib/moment/moment-2.13.0.js',