attempt at #3, pattern in MBean ObjectName

Each mbean name given in the XML configuration file is expanded using
the query method of MBeanServer.

The query method takes in an ObjectName and returns all registered MBeans that
matches it.

If there is an error, for example a typo in the configuration, the malformed
MBean isn't added to the MBeanSampler.
Ignore malformed patterns

Properly formed patterns are expanded into ObjectName
 and queried individually.
build full pname from pattern