[BEANUTILS-470] NumberConverter now deals with BigDecimal objects correctly.

If a BigDecimal object is passed to the converter it is now directly returned
without trying a conversion that will cause a loss of precision.

Thanks to Tommy Tynjä for the patch.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/beanutils/trunk@1628829 13f79535-47bb-0310-9956-ffa450edef68
[BEANUTILS-470] Updated changes.xml.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/beanutils/trunk@1628830 13f79535-47bb-0310-9956-ffa450edef68