[beanutils] Generic implementations of toString, hashCode, equals() for DynaBean and DynaClass

This patchset includes a new DynaUtils class containing builder methods for hash
codes and string representations of DynaBeans and DynaClasses, abstract base
classes for DynaBean and DynaClass that use DynaUtils to implement these
methods, and patches for existing DynaBean and DynaClass implementations to make
them extend these abstract base classes.

Kris