Update changelog for v2.4.7
Update changelog for v2.4.7

Change-Id: I4de84bdb4b93dacba54aa01936c16e2fd62bfc32

shaka-project/shaka-player,tvoli/shaka-player,tvoli/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player