Allow to specify session cookie / parameter name.

Now it is not possible to specify at balancer a session cookie / parameter name different from what is used at server.

This would be useful for implementing "Sticky Session duration". This means that sessions would be stuck to one server for a period of time. When this period of time goes by, the session could be stuck to a different server that is less loaded than previous one.

The scenario in which "sticky session duration" makes sense is a distributable application that needs to have sticky session but not for the entire session.

Some useful documentation:
http://docs.aws.amazon.com/elasticloadbalancing/latest/classic/elb-sticky-sessions.html#enable-sticky-sessions-duration
http://docs.aws.amazon.com/elasticloadbalancing/latest/classic/elb-sticky-sessions.html#enable-sticky-sessions-application
https://developer.jboss.org/thread/273861
https://developer.jboss.org/thread/275361
https://stackoverflow.com/questions/42025998/sticky-session-duration

A way to implement the functionality that allows to specify the session cookie / parameter name is attached in two files. Additionally, a file (META-INF/services/org.jboss.modcluster.container.catalina.EngineFactory) change, specifying the new factory, is needed.