This commit introduces the `CSpanLiveIE` class to add support for C-SPAN
live streams. These streams are based on the `BrightcoveNewIE` class
which requires Adobe Pass MSO authentication.
In order to support this new information extractor, `BrightcoveNewIE`
had to be updated to support an optional Akamai token ('hdnts' query
parameter) in the final m3u8 URL used by Brightcove.
