How do I upgrade Rubygems in Bluemix?
<p>How do I upgrade Rubygems in Bluemix? I'm getting this message:</p>

<blockquote>
  <p>Rubygems 2.0.14.1 is not threadsafe, so your gems must be installed one at a time. Upgrade to Rubygems 2.1.0 or higher to enable parallel gem installation.</p>
</blockquote>

<p>and since I have a lot of gems, I'd really like to use this feature.
I'm using Ruby buildpack version 1.6.7 and Ruby 2.0.0.</p>