Adding UMD wrapper

https://github.com/umdjs/umd/blob/master/jqueryPluginCommonjs.js

Thanks for the nudge @AndrewEastwood and @jd-boyd
Closes digitalBush#65
Closes digitalBush#241

Author: digitalBush

dist/jquery.maskedinput.js

@@ -4,7 +4,9 @@
     Licensed under the MIT license (http://digitalbush.com/projects/masked-input-plugin/#license)
     Version: 1.3.1
 */
-!function($) {
+!function(factory) {
+    "function" == typeof define && define.amd ? define([ "jquery" ], factory) : factory("object" == typeof exports ? require("jquery") : jQuery);
+}(function($) {
     function getPasteEvent() {
         var el = document.createElement("input"), name = "onpaste";
         return el.setAttribute(name, ""), "function" == typeof el[name] ? "paste" : "input";
@@ -173,4 +175,4 @@
             }));
         }
     });
-}(jQuery);
+});

dist/jquery.maskedinput.min.js

@@ -1,4 +1,15 @@
-(function($) {
+(function (factory) {
+    if (typeof define === 'function' && define.amd) {
+        // AMD. Register as an anonymous module.
+        define(['jquery'], factory);
+    } else if (typeof exports === 'object') {
+        // Node/CommonJS
+        factory(require('jquery'));
+    } else {
+        // Browser globals
+        factory(jQuery);
+    }
+}(function ($) {
 
 function getPasteEvent() {
     var el = document.createElement('input'),
@@ -415,4 +426,4 @@ $.fn.extend({
 		});
 	}
 });
-})(jQuery);
+}));