Fixed a regression after the generification of converters.

If LocaleConverterUtilsBean cannot find a converter for the specified target
class, it uses the default string converter. This converter can now fail if
it does not support the target type.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/beanutils/branches/java5@1538226 13f79535-47bb-0310-9956-ffa450edef68