Merged with latest Pistachitos branch + added NZBGet custom username support

I have merged the latest Pistachitos branch because it contains some crucial fixes ( this ao: https://github.com/mr-orange/Sick-Beard/issues/228 )
Also I added support for a custom NZBGet username, this is possible since the latest NZBGet release 11.0. It will also still work with older versions. These modifications are taken from the XBian fork https://github.com/xbianonpi/Sick-Beard-TPB