add event for playing video
added more remote functions

play / pause / channel up / down / fwd / rewind
retry if network issue on renewing subscription
Ignore non-Sky devices which respond to our UPnP requests

If you've got another UPnP device which responds first, many bad things happen. (In my case, Philips Hue)
Merge pull request #1 from paulcull/master

add event for playing video
Merge pull request #10 from lgladdy/master

Adds @paulcull's pull request for video playing events, plus support multiple UPnP responding devices (such as a Philips Hue). Thanks @lgladdy