Update CHANGELOG with recent changes to Sky's pub package
Update CHANGELOG with recent changes to Sky's pub package

TBR=ianh@google.com

Review URL: https://codereview.chromium.org/1104093004

flutter/flutter,flutter/flutter,Hixie/flutter,cbracken/flutter,Hixie/flutter,tvolkert/flutter,turnidge/flutter,tvolkert/flutter,cbracken/flutter,Hixie/flutter,tvolkert/flutter,tvolkert/flutter,tvolkert/flutter,cbracken/flutter,jason-simmons/flutter,aghassemi/flutter,flutter/flutter,jason-simmons/flutter,flutter/flutter,flutter/flutter,Hixie/flutter,Hixie/flutter,tvolkert/flutter,flutter/flutter,flutter/flutter,turnidge/flutter,jason-simmons/flutter,Hixie/flutter,flutter/flutter,cbracken/flutter,Hixie/flutter,tvolkert/flutter,tvolkert/flutter,jason-simmons/flutter,tvolkert/flutter,aghassemi/flutter,cbracken/flutter,cbracken/flutter,Hixie/flutter,aghassemi/flutter,cbracken/flutter,flutter/flutter,turnidge/flutter,Hixie/flutter,flutter/flutter,aghassemi/flutter,turnidge/flutter,cbracken/flutter,cbracken/flutter,cbracken/flutter,turnidge/flutter,Hixie/flutter,tvolkert/flutter