Fix speed change bug.
Fix slider and pause bugs.
BLD-424. Update CHANGELOG.rst.
add user_id to tracking context

AN-213
update authors file
Merge pull request #1527 from edx/anton/video-speed-change-bug

Video player: speed change bug
Merge pull request #1478 from mulby/gabe/track-user-id

add user_id to tracking context
Disable multiple YT test due to flakinesss
Merge pull request #1528 from edx/will/disable-yt-js-test

Disable multiple YT test due to flakinesss