AVPlayerLayer videoGravity support on iOS#10

bedemiralp wants to merge 2 commits intoquipper:masterquipper/react-native-brightcove-player:masterfrom

TrueRowing:bd/ios-AVPlayerLayer-videoGravityTrueRowing/react-native-brightcove-player:bd/ios-AVPlayerLayer-videoGravityCopy head branch name to clipboard