[BEANUTILS-454] BeanUtilsBean.copyProperties() handles null values differently.

No longer a ConversionException is thrown for null values for certain data
types. A special handling for null values was added in the copy method.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/beanutils/trunk@1546736 13f79535-47bb-0310-9956-ffa450edef68
[BEANUTILS-454] Updated changes.xml and release notes.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/beanutils/trunk@1546737 13f79535-47bb-0310-9956-ffa450edef68