cmd/ursrv: Add google maps api key (fixes #5296) (#5303)

cmd/ursrv/static/index.html

@@ -17,7 +17,7 @@ found in the LICENSE file.
   <link href="static/bootstrap/css/bootstrap.min.css" rel="stylesheet">
   <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
   <script type="text/javascript" src="static/bootstrap/js/bootstrap.min.js"></script>
-  <script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?libraries=visualization"></script>
+  <script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?libraries=visualization&key=AIzaSyDk5WJ8s7ueLKb99X5DbQ-vkWtPDAKqYs0"></script>
   <style type="text/css">
     body {
       margin: 40px;