title: avoid http checking when installing a home made gem
body: <p>I'm working on a set of gems for my application. </p>
  
  <p>When installing any of my own gems, the gem program will check rubugems specs (possibly for dependencies). With a verbose flag I can see messages like : </p>
  
  <pre><code>GET http://rubygems.org/latest_specs.4.8.gz
  302 Found
  GET http://production.s3.rubygems.org/latest_specs.4.8.gz
  200 OK
  GET http://rubygems.org/specs.4.8.gz
  </code></pre>
  
  <p>The issue is that I'm working on those gems, and that I package/reinstall a number of times every day, and the installation process is quite long.</p>
  
  <p>As I'm pretty sure that all the external gem dependencies are satisfied, is there a way to tel gem <em>not to check</em> the dependencies from rubygems.org, and avoid, possibly slow http traffic ?</p>
  
  <p>Regards, </p>
  
  <p>_dl</p>