Added BeanIntrospectionData class.

This internal class is used in future by PropertyUtilsBean to cache information
about bean classes and their available properties.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/beanutils/trunk@1555222 13f79535-47bb-0310-9956-ffa450edef68
Changed the cache in PropertyUtilsBean to use the new BeanIntrospectionData class.

Information about bean classes obtained via introspection is now stored in form
of BeanIntrospectionData objects.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/beanutils/trunk@1555224 13f79535-47bb-0310-9956-ffa450edef68