added latest rubies: ruby-1.9.3-p551, ruby-2.0.0-p598 and ruby-2.1.5

share/ruby-build/1.9.3-p551

+install_package "yaml-0.1.6" "http://pyyaml.org/download/libyaml/yaml-0.1.6.tar.gz#7da6971b4bd08a986dd2a61353bc422362bd0edcc67d7ebaac68c95f74182749" --if needs_yaml
+install_package "ruby-1.9.3-p551" "http://cache.ruby-lang.org/pub/ruby/1.9/ruby-1.9.3-p551.tar.gz#bb5be55cd1f49c95bb05b6f587701376b53d310eb1bb7c76fbd445a1c75b51e8"

share/ruby-build/2.0.0-p598

+install_package "openssl-1.0.1j" "https://www.openssl.org/source/openssl-1.0.1j.tar.gz#1b60ca8789ba6f03e8ef20da2293b8dc131c39d83814e775069f02d26354edf3" mac_openssl --if has_broken_mac_openssl
+install_package "ruby-2.0.0-p598" "http://cache.ruby-lang.org/pub/ruby/2.0/ruby-2.0.0-p598.tar.gz#4136bf7d764cbcc1c7da2824ed2826c3550f2b62af673c79ddbf9049b12095fd" standard verify_openssl

share/ruby-build/2.1.5

+install_package "openssl-1.0.1j" "https://www.openssl.org/source/openssl-1.0.1j.tar.gz#1b60ca8789ba6f03e8ef20da2293b8dc131c39d83814e775069f02d26354edf3" mac_openssl --if has_broken_mac_openssl
+install_package "ruby-2.1.5" "http://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.5.tar.gz#4305cc6ceb094df55210d83548dcbeb5117d74eea25196a9b14fa268d354b100" ldflags_dirs standard verify_openssl