[Bigflix] Add new extractor for bigflix.com

Add an IE to support bigflix.com. It uses some sort of silverlight
plugin whose video url is being populated using base64 encoded
flashvars. So it is quite straightforward to extract.

youtube_dl/extractor/__init__.py

@@ -61,6 +61,7 @@ from .beeg import BeegIE
 from .behindkink import BehindKinkIE
 from .beatportpro import BeatportProIE
 from .bet import BetIE
+from .bigflix import BigflixIE
 from .bild import BildIE
 from .bilibili import BiliBiliIE
 from .bleacherreport import (