[KARAF-2513] management boot can not process MBean without implement DynamicMBean interface

This fixes the issue. The problem was that the InvocationTargetException was't unwrapped before it was passed to the caller.
Verified with the ManagedCamelContext as reported in the bug.
Also added unit test.


git-svn-id: https://svn.apache.org/repos/asf/karaf/trunk@1544153 13f79535-47bb-0310-9956-ffa450edef68