title: firefox addon-sdk : handle http request timeout
body: <p>I'm building a firefox add-on using the add-on sdk. I need to make a http request to a certain page and I want to handle the connection timeout but couldn't find anything in the api: <a href="https://addons.mozilla.org/en-US/developers/docs/sdk/latest/modules/sdk/request.html" rel="nofollow">https://addons.mozilla.org/en-US/developers/docs/sdk/latest/modules/sdk/request.html</a></p>
  
  <p>What I'm actually looking is a callback in case the client couldn't connect to the server.</p>
  
  <p>Is there a way to achieve this?</p>