Update contributors and licence files, adding Gibus and I in it, and the content of the AGPL licence.
src.dir = src
lib.dir = lib
doc.dir = doc
build.dir = build
product.name = yuicompressor
version.number = 2.4.2
jar.name = ${product.name}-${version.number}.jar
dist.package.name = ${product.name}-${version.number}