Merge remote-tracking branch 'upstream/master'
Added check for function apache_request_headers (since it isn't available when PHP runs as FPM).
Add stream selector

Initial commit - dependency on API changes
Add UX handlers for source switching
Implement API calls
Update player data and scrubber thumb rotator on switch
Merge branch '2.20-Oct-19' into streamSelector
Enable UI when source switch ended
temp pull request while FEC-2250 is fixed
updated docs for widevine test
removed unused file, removed unused variable validEventList
bump v2.21
#FEC-869 #comment don't show duration in live, dynamically adjust player duration, update back to live ui
remove liveBackBtn in VOD entries
Merge pull request #1160 from kaltura/ga-cleanup

GA: removed unused file, removed unused variable validEventList
Merge pull request #1137 from kaltura/temp-widevine-ac-branch

Temp widevine ac branch
Support adjusting playhead in live HDS too
Merge branch '2.22-Nov-30' into streamSelector
Update CaptionsCustomVarsTTML.qunit.html

added note per incompatibility of CMML with some style rules
FEC-2312 set CORS header for JSON config POST on kgit