Updating changelog.
Updating changelog.

Change-Id: Iaff60b0d78fa45e4ab31c05d9a65bb9d012077ff

claywilkinson/play-games-plugin-for-unity,claywilkinson/play-games-plugin-for-unity,claywilkinson/play-games-plugin-for-unity,claywilkinson/play-games-plugin-for-unity