Changes from commons.modeler:

- use DynamicMBean
- remove methods not used in tomcat and redundant/not very generic
- must be created from the ManagedBean - I don't think there were any direct
uses, but now it is required.
- some of the gratuituous flexibility removed - instead this is more predictive and
strict with the use cases.
- all Method and metadata is stored in ManagedBean. BaseModelBMean and ManagedBean act
like Object and Class.
- setModelMBean is no longer called on resources ( not used in tomcat )
- no caching of Methods for now - operations and setters are not called repeatedly in most
management use cases. Getters should't be called very frequently either - and even if they
are, the overhead of getting the method should be small compared with other JMX costs ( RMI, etc ).
We can add getter cache if needed.
- removed unused constructor, fields

TODO:
- clean up catalina.mbeans, stop using weird inheritance