Support for Jmx (and Integration) autoconfig in parent contexts

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

spring-boot-samples/spring-boot-sample-integration/pom.xml

@@ -23,6 +23,10 @@
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-integration</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-actuator</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.integration</groupId>
 			<artifactId>spring-integration-jmx</artifactId>