Get rid of obsolete XML application context config

src/main/webapp/WEB-INF/arsnova-servlet.xml

-<?xml version="1.0" encoding="UTF-8"?>
-<beans xmlns = "http://www.springframework.org/schema/beans"
-	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
-</beans>

src/main/webapp/WEB-INF/web.xml

@@ -22,6 +22,10 @@
 	<servlet>
 		<servlet-name>arsnova</servlet-name>
 		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
+		<init-param>
+			<param-name>contextClass</param-name>
+			<param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
+		</init-param>
 		<init-param>
 			<param-name>throwExceptionIfNoHandlerFound</param-name>
 			<param-value>true</param-value>