Log Message:
youtube-dl: Update to 20190727

Changes:
20190727
--------
Extractors
+ [yahoo:japannews] Add support for yahoo.co.jp (#21698, #21265)
+ [discovery] Add support go.discovery.com URLs
* [youtube:playlist] Relax video regular expression (#21844)
* [generic] Restrict --default-search schemeless URLs detection pattern
  (#21842)
* [vrv] Fix CMS signing query extraction (#21809)