title: install rails on Ubuntu fails, probably due to missing bundler gem
body: <p>I cannot install rails on ubuntu 11.4. 
  I tested this twice on my workstation and then on a virtual machine freshly installed.
  Rails install will report error.</p>
  
  <p>Hint: Also I cannot find the bundle command which should be installed by 'gem install bundler'</p>
  
  <p>I skipped from the log all successful output.</p>
  
  <pre><code>test@ubuntu:~$ sudo apt-get install  ruby-full
  [...]
  test@ubuntu:~$ sudo apt-get install rubygems1.8
  [...]
  test@ubuntu:~$ sudo gem install rdoc
  [...]
  test@ubuntu:~$ sudo gem install bundler
  [...]
  test@ubuntu:~$ sudo gem install rails
  [...]
  Installing ri documentation for rails-3.0.7...
  file 'lib' not found
  Installing RDoc documentation for activesupport-3.0.7...
  [...]
  Installing RDoc documentation for rails-3.0.7...
  file 'lib' not found
  </code></pre>