+ * A handler that shuts the server down on a valid request. Used to do "soft" restarts from Java.
+ * If _exitJvm is set to true a hard System.exit() call is being made.
+ * If _sendShutdownAtStart is set to true, starting the server will try to shut down an existing server at the same port.
+ * If _sendShutdownAtStart is set to true, make a http call to
+ * "http://localhost:" + port + "/shutdown?token=" + shutdownCookie
+ * in order to shut down the server.