Update Gruntfile.js.

* remove unneeded variable
* move jshint first
* update uglify-js options

Gruntfile.js

@@ -2,27 +2,29 @@ module.exports = function(grunt) {
 
     // Project configuration.
     grunt.initConfig({
-        pkg: grunt.file.readJSON('package.json'),
-        uglify: {
-            options: {
-                preserveComments: 'some'
-            },
-            build: {
-                src: 'jquery.mousewheel.js',
-                dest: 'build/jquery.mousewheel.min.js'
-            }
-        },
         jshint: {
             options: {
                 jshintrc: '.jshintrc'
             },
             all: ['*.js']
+        },
+        uglify: {
+            options: {
+                compress: true,
+                mangle: true,
+                preserveComments: 'some',
+                report: 'gzip'
+            },
+            build: {
+                src: 'jquery.mousewheel.js',
+                dest: 'build/jquery.mousewheel.min.js'
+            }
         }
     });
 
     // Load the plugin that provides the 'uglify' task.
-    grunt.loadNpmTasks('grunt-contrib-uglify');
     grunt.loadNpmTasks('grunt-contrib-jshint');
+    grunt.loadNpmTasks('grunt-contrib-uglify');
 
     // Default task(s).
     grunt.registerTask('default', ['jshint', 'uglify']);