[clyp] Add extractor

Update __init__.py

[clyp.it] Extract ID idiomatically and make duration and description optional

youtube_dl/extractor/__init__.py

@@ -90,6 +90,7 @@ from .cliphunter import CliphunterIE
 from .clipsyndicate import ClipsyndicateIE
 from .cloudy import CloudyIE
 from .clubic import ClubicIE
+from .clyp import ClypIE
 from .cmt import CMTIE
 from .cnet import CNETIE
 from .cnn import (