Adding a setup_ruby_primer script.

The script installs all of the pe-ruby* packages that ship with
PE and creates a file '.extendingrc' in /root/. So that when the
bashrc or zshrc file is execed the $PATH is correctly set.
Adding the remove script for the setup script.
Updating the bashrc to set the PATH correctly.
Update the zshrc to set the PATH correctly.
Merge pull request #200 from klynton/fix-trainvm-18

Fix TRAINVM-18