Problem with sites which do not set a referer

[ktamp]

If a site does not set a referer (e.g. fedoraproject.org), clicking on a link does not propagate the message to uGet Download Manager, while right-clicking on the link and selecting "Download with uGet" works.

In order for clicking on a link to work for these sites too, the following fix has to be applied to function read_message() in uget-integrator:
referer = data['Referer']
should be replaced with
referer = data.get('Referer', '')