Upgrade youtube_dl to 2018.05.18

[fabaff]

Description

• Changelog: https://github.com/rg3/youtube-dl/blob/master/ChangeLog

Tested with the following configuration:

media_extractor:

Service call:

{"entity_id": "media_player.mpd", "media_content_id": "https://www.youtube.com/watch?v=gHSN4DmjPas", "media_content_type": "music"}

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

If the code communicates with devices, web services, or third-party tools:

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.