Extra info

Something else I found helpful along the way (as I had old stuff installed):

gem uninstall --install-dir /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8 rails

RSpec Issues

zsh: /usr/local/bin/spec: bad interpreter: /usr/local/bin/ruby: no such file or directory

The issue is that my ruby isn't installed at /usr/local/bin/ruby but rather /usr/bin/ruby therefore I created a simlink.

Solution

zsh: /usr/local/bin/bundle: bad interpreter: /usr/local/bin/ruby: no such file or directory

% which ruby
/usr/bin/ruby

% cd /usr/local/bin/  
/usr/local/bin% ln -s /usr/bin/ruby ruby