def define_on_distro_release(distro, release, name, version=nil)
      distro_releases[[distro, release]] << [name, version]
    end
def define_on_distro_release(distro, release, name, version=nil)
      distro_releases[[distro, release]] << [name, version]
    end
Define the package name and an optional version constraint for a distribution release
 @param distro[Symbol] The distribution name like :ubuntu, :debian ...
 @param release[Symbol] The distribution release like :precise for ubuntu 12.04
 @param name[String] A package name
 @param version[String, nil] A version constraint