HTTP session persistence

As Magnolia currently does not provide serialization of classes for HTTP clustering, persistence of HTTP sessions is disabled by default in the configuration of the Tomcat container which is bundled together with Magnolia. Disabling session persistence will remove the java.io.NotSerializableException warning from the logs. To disable the persistence in Tomcat bundled together with a previous version of Magnolia, please follow the instructions available at the apache.org website (https://tomcat.apache.org/tomcat-7.0-doc/config/manager.html#Disable_Session_Persistence).