Added Newgrounds support

youtube_dl/extractor/__init__.py

@@ -68,6 +68,7 @@ from .myvideo import MyVideoIE
 from .naver import NaverIE
 from .nba import NBAIE
 from .nbc import NBCNewsIE
+from .newgrounds import NewgroundsIE
 from .ooyala import OoyalaIE
 from .orf import ORFIE
 from .pbs import PBSIE