CSR UI breaks any site with attribute routes registration

Description

CSR UI calls routes.MapHttpRoute in its initialization module. This should be call after config.MapHttpAttributeRoutes() which any site with attribute routes should do. However, currently there is no guarantee for such order, therefore CSR UI will break those sites with this error.

{
    "Message": "An error has occurred.",
    "ExceptionMessage": "The object has not yet been initialized. Ensure that HttpConfiguration.EnsureInitialized() is called in the application's startup code after all other initialization code.",
    "ExceptionType": "System.InvalidOperationException",
    "StackTrace": "   at System.Web.Http.Routing.RouteCollectionRoute.get_SubRoutes()\r\n   at System.Web.Http.Routing.RouteCollectionRoute.GetRouteData(String virtualPathRoot, HttpRequestMessage request)\r\n   at System.Web.Http.WebHost.Routing.HttpWebRoute.GetRouteData(HttpContextBase httpContext)"
}