Merge remote-tracking branch 'Huarong/master'

diff --cc youtube_dl/extractor/__init__.py
index 21e9e5d37234a9535555fcdc6e1df3a67e764073,3a08d676fb40db39f09f1c2eb09618b0516552f0..6b5037c8c18092c8fdafd3675b0baa9d1327cadd
--- 1/youtube_dl/extractor/__init__.py
--- 2/youtube_dl/extractor/__init__.py
+++ b/youtube_dl/extractor/__init__.py
@@@ -65,11 -53,9 +65,12 @@@ from .pornotube import PornotubeI
  from .rbmaradio import RBMARadioIE
  from .redtube import RedTubeIE
  from .ringtv import RingTVIE
 +from .ro220 import Ro220IE
  from .roxwel import RoxwelIE
 +from .rtlnow import RTLnowIE
  from .sina import SinaIE
 +from .slashdot import SlashdotIE
+ from .sohu import SohuIE
  from .soundcloud import SoundcloudIE, SoundcloudSetIE
  from .spiegel import SpiegelIE
  from .stanfordoc import StanfordOpenClassroomIE