Merge pull request #52 from guilleiguaran/definitions

Definitions for jruby-dev, ruby-trunk and update for rbx-dev

share/ruby-build/1.9.4-dev

+use_gcc42_on_lion
+install_package "yaml-0.1.4" "http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz"
+install_git "ruby-1.9.4-dev" "https://github.com/ruby/ruby.git" "trunk" autoconf standard
+install_package "rubygems-1.8.10" "http://production.cf.rubygems.org/rubygems/rubygems-1.8.10.tgz" ruby

share/ruby-build/jruby-1.7.0-dev

+install_package "jruby-1.7.0.dev" "http://ci.jruby.org/snapshots/jruby-bin-1.7.0.dev.tar.gz" jruby
+install_package "rubygems-1.6.2" "http://production.cf.rubygems.org/rubygems/rubygems-1.6.2.tgz" ruby

share/ruby-build/rbx-2.0.0-dev

-install_git "rubinius-2.0.0-dev" "https://github.com/rubinius/rubinius.git" "2.0.0pre" rbx
+install_git "rubinius-2.0.0-dev" "https://github.com/rubinius/rubinius.git" "master" rbx
 install_package "rubygems-1.8.10" "http://production.cf.rubygems.org/rubygems/rubygems-1.8.10.tgz" ruby