Build: Update the licenses attribute to singular license

Specifying the type and URL is deprecated:
https://docs.npmjs.com/files/package.json#license

Author: jzaefferer

package.json

@@ -45,12 +45,7 @@
 		"url": "git://github.com/jquery/jquery-ui.git"
 	},
 	"bugs": "http://bugs.jqueryui.com/",
-	"licenses": [
-		{
-			"type": "MIT",
-			"url": "https://github.com/jquery/jquery-ui/blob/master/LICENSE.txt"
-		}
-	],
+	"license": "MIT",
 	"scripts": {
 		"test": "grunt"
 	},