title: Firefox extension include script in main.js file
body: <p>I am writing an extension for firefox and having a problem including scripts into the main.js (background) file ...</p>
  
  <p>In my case I would like to include for example jquery.js and config.js but I can't see how to do it properly.</p>
  
  <p>In my chrome extension I just do that on the manifest file but I would like the equivalent in firefox.</p>
  
  <p>Thank you for your help,
  jdmry</p>