[karrierevideos] add support for www.karrierevideos.at (closes #5354)

youtube_dl/extractor/__init__.py

@@ -244,6 +244,7 @@ from .kaltura import KalturaIE
 from .kanalplay import KanalPlayIE
 from .kankan import KankanIE
 from .karaoketv import KaraoketvIE
+from .karrierevideos import KarriereVideosIE
 from .keezmovies import KeezMoviesIE
 from .khanacademy import KhanAcademyIE
 from .kickstarter import KickStarterIE