Instale o Ruby 1.8.7 do rbenv com macports

• Instale o xquartz
• instalar xcode
• baixar ferramentas de desenvolvedor

sudo port install gcc_select
sudo port install apple-gcc42
port select --list gcc
sudo port select --set gcc apple-gcc42
CONFIGURE_OPTS="--without-tk" rbenv install 1.8.7-p370