Merge pull request #730 from dangreen/master

Throw error if call in node

Sortable.js

@@ -23,6 +23,12 @@
 	}
 })(function () {
 	"use strict";
+	
+	if (typeof window == "undefined" || typeof window.document == "undefined") {
+		return function() {
+			throw new Error( "Sortable.js requires a window with a document" );
+		}
+	}
 
 	var dragEl,
 		parentEl,