For 14.04 I found the following PPAs that come with Ruby 2.x
Adds Ruby 2.1 to Ubuntu 14.04
sudo add-apt-repository ppa:brightbox/ruby-ng
I also found in GoRails a set of instructions to install Ruby on 14.04 but I am guessing since they are long you would want a PPA instead.
Adds Ruby 1.9, 2.0 or 2.1 to Ubuntu 14.04
sudo add-apt-repository ppa:brightbox/ruby-ng-experimental
After you add one of them simply:
sudo apt-get update
sudo apt-get install ruby2.1 -- In the case you want 2.1
