Changes made:
1. AFCVideoIE, CarltonFCVideoIE: fixed the issue to find the correct
video media id. (thanks to pzhlkj6612a)
2. AFCVideoIE: added support for pages where mediaId is unavailable
in webpage
3. CarltonFCVideoIE: split from AFCVideoIE because of point 2 as the
variation is specific to AFCVideo
4. Updated test cases