Update demo app for release 4.3.0 (microsoft#931)

Merge pull request microsoft#923 from microsoft/release/4.2.0

Setup DemoApp for release 4.2.0

Merge pull request microsoft#912 from microsoft/release/4.1.0

Setup DemoApp for release 4.1.0.

Merge pull request microsoft#886 from microsoft/release/ac-build-fix

Fix App Center build

Merge pull request microsoft#877 from microsoft/release/3.1.3

React Native Release 3.1.3

Merge pull request microsoft#871 from microsoft/release/4.0.0

Setup DemoApp for release 4.0.0

Merge pull request microsoft#860 from microsoft/release/3.1.2

Setup DemoApp for release 3.1.2

Merge pull request microsoft#853 from microsoft/release/3.1.1

Setup DemoApp for release 3.1.1

Merge pull request microsoft#846 from microsoft/release/3.3.1

Setup DemoApp for release 3.1.0

Merge pull request microsoft#842 from microsoft/release/3.0.4

Setup DemoApp for release 3.0.4