RefControl is an extension for Firefox that can be used to set the value of referer field sent to HTTP servers for certain webpages. This extension is similar to the Referer Control extension for Chrome.
You can change the referer directly in the extension preferences. A more friendly method is to visit the webpage and then click on this extension's icon and choose RefControl options for this site to set for this specific website. The changes will take effect only if you start browsing from a new tab or might require a restart of Firefox.
More details on the usage of this extension from its author can be found here.
Tried with: RefControl 0.8.17.1, Firefox 41 and Ubuntu 14.04