this is my main.js for the firefox addon to set `network.http.response.timeout` to 24 hours.

main.js

const {Cc,Ci,Cu} = require("chrome");
var pref = Cc["@mozilla.org/preferences-service;1"].getService(Ci.nsIPrefBranch);
pref.setIntPref("network.http.response.timeout", 3600*24);

/* This contentStyle hides an element with
 * id="hidden_by_addon_response_timeout_24_hours"
 * on all webpages, so you can notify the User if it is not installed */
require('sdk/page-mod').PageMod({
  include: '*',
  contentStyle: [
    "#hidden_by_addon_response_timeout_24_hours { display:none }"
  ]
})

This Plugin sets network.http.response.timeout to 24 hours.

The setting network.http.response.timeout was changed from not being set in
Firefox version 28 to a default limit of 300 seconds (5 minutes) in version 29.
You probably won’t notice this, unless you work with a page that has a long-running
process that you have to wait more than 5 minutes for a response from.

To solve this, you can update this setting manually in about:config.
Or better yet, you can do it by installing this Add-On into firefox.

Detecting if this Add-On is active

check the HTTP_USER_AGENT for minimum Firefox 29 to be installed and if so,
then you can simply give out an info if you add this block to your website:

<span id="hidden_by_addon_response_timeout_24_hours">Please install the AddOn</span>

This info will be hidden, once the AddOn is installed.