title: how to change firefox proxy settings using xpcom
body: <p>I have a proxy server running on localhost (127.0.0.1) and i have <strong>grown tired</strong> of having to train users on how to switch proxies in firefox to bypass blocked websites.<br>
   I decided to write an addon. I wonder how to use <strong>xpcom</strong> to tell firefox to use a certain proxy eg<br>
  for http, use 127.0.0.1 port 8080.<br>
  Examples on the internet are scarce.  </p>
  
  <p>Thanks</p>