Usage:
<taskdef name="fileprefixer" classname="org.bellard.fileprefixer.FilePrefixerTask" classpath="dist/file-prefixer-0.0.1.jar"/>
<fileprefixer toprefix="build/eqemu-licence.txt" todir="dist" verbose="true">
fileset dir="dist">
<include name="**/*.java"/>
</fileset>
</fileprefixer>