Added Maven Javadoc plugin configuration to allow make the Javadoc JAR and documentation in the `javadoc` directory.
Added Maven Javadoc plugin configuration to allow make the Javadoc JAR and documentation in the `javadoc` directory.

guhb/thumbnailator,giflw/thumbnailator,coobird/thumbnailator,qingsong-xu/thumbnailator,ymero/thumbnailator