Add optional support for progressive HTTP download

There's been a lot of issues caused by bugs in XBMC's support for RTMP, and considering the RTMP servers are no longer unmetered, we may as well use HTTP streams considering it should be a lot more stable and tested in XBMC. This PR adds it in as an option under the addon settings.

The actual streams are fetched using the new iView website to grab the new series ID, and use that to filter the Smart TV RSS feeds and grab the url for the episode we want to watch.

/cc @andybotting