[KARAF-2568] Backport to 2.x of JMXSecurityMBean

The JMXSecurityMBean contains four canInvoke() variants which can inform the client whether a certain JMX operation can be invoked or not. This information is provided for the current JMX user.


git-svn-id: https://svn.apache.org/repos/asf/karaf/branches/karaf-2.x@1545218 13f79535-47bb-0310-9956-ffa450edef68