Make xml-doclet java 1.6 compatible

Although java 1.6 is not officially supported anymore, there still are a lot of unfortunate souls who need to keep on using it for various reasons. (I am one of them.) I need selenium2library's java port to run on 1.6 and that in turn needs xml-doclet.

The change needed to make xml-doclet java 1.6 compliant is only one line. It would be very helpful for us, if you could include this change in a future release of selenium2library for java.

Thanks!