install_package "jruby-1.7.0.preview2" "http://jruby.org.s3.amazonaws.com/downloads/1.7.0.preview2/jruby-bin-1.7.0.preview2.tar.gz#cac0881da9d53905fe591a692583cce1e5c40fbca19f0218b6490ff3305185bb" jruby