Speed up servlet start

- Set metadata-complete="true" attribute on the <web-app> element.
- Add an empty <absolute-ordering /> element.

See:
https://wiki.apache.org/tomcat/HowTo/FasterStartUp#Configure_your_web_ap
plication

On my (old) machine, this reduces startup time with Jetty from 137580ms
to 20166ms.

openid-connect-server-webapp/src/main/webapp/WEB-INF/web.xml

@@ -17,7 +17,10 @@
 -->
 <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
 	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
+	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
+	metadata-complete="true">
+
+	<absolute-ordering />
 
 	<!-- The definition of the Root Spring Container shared by all Servlets 
 		and Filters -->