title: ActiveSupport requires Ruby version >= 1.8.7 on Ubuntu
body: <p>I'm currently setting up a new server, and started off with an Ubuntu 8.04 image with a version of Ruby and Rails already preinstalled (I thought it would be easier), and after getting my app running (with a few gems installed), the command line is throwing a wobbly, and trying to install the "Paperclip" gem, is giving the following error:</p>
  
  <pre><code> activesupport requires ruby version &gt;= 1.8.7
  </code></pre>
  
  <p>Running ruby -v tells me I'm on 1.8.6, but for the life of me, I have no idea how to update Ruby from the command line.</p>
  
  <p>So, any advice for a) how to get Paperclip to work and b) ensure activesupport doesn't run into this error again, would be most welcome!</p>