Remove build_sky_apk.dart
Remove build_sky_apk.dart

This script has been subsumed by `flutter apk`.

Hixie/flutter,tvolkert/flutter,turnidge/flutter,tvolkert/flutter,tvolkert/flutter,cbracken/flutter,tvolkert/flutter,cbracken/flutter,tvolkert/flutter,Hixie/flutter,aghassemi/flutter,Hixie/flutter,flutter/flutter,turnidge/flutter,cbracken/flutter,tvolkert/flutter,cbracken/flutter,tvolkert/flutter,Hixie/flutter,turnidge/flutter,cbracken/flutter,Hixie/flutter,cbracken/flutter,flutter/flutter,cbracken/flutter,cbracken/flutter,Hixie/flutter,cbracken/flutter,aghassemi/flutter,Hixie/flutter,tvolkert/flutter,flutter/flutter,aghassemi/flutter,flutter/flutter,flutter/flutter,flutter/flutter,flutter/flutter,flutter/flutter,flutter/flutter,tvolkert/flutter,aghassemi/flutter,cbracken/flutter,turnidge/flutter,turnidge/flutter,Hixie/flutter,Hixie/flutter,Hixie/flutter,tvolkert/flutter,flutter/flutter