Cara Downgrade Ruby Ke Versi 1.8.7 dari versi terbaru menjadi bersi 1.8

For CentOS and RedHat:
yum erase ruby ruby-libs
yum install ruby-1.8.*
yum install rubygems

For Ubuntu:
apt-get install ruby1.8 rubygems (may already be installed)
update-alternatives --set ruby "/usr/bin/ruby1.8"
update-alternatives --set gem "/usr/bin/gem1.8"