When there are parent contexts we already had a strategy for registering
the actuator endpoints, but not the regular JMX or Integration MBeans.
This chnage makes the autoconfigs for JMX aware of the parent context.
Also adds a sample with a parent context.
See gh-847
They all want to create an MBeanServer and when that happens
user sees no MBeans, or sometimes just one set (Spring Core,
Spring Integration or Spring Boot). To harmonise them we
create a @Bean of type MBeanServer and link to it in the
other autoconfigs
Fixes gh-1046
Long package names are really unnecessary in samples and they
just clutter things up. Also Spring Loaded doesn't work with
org.sfw packages, so to demo that technology you need a
different package name.