Update NetStandard.Library dependency to NETStandard.Library 1.6.1. (A…

…pp-vNext#229)

Update NetStandard.Library dependency to NETStandard.Library 1.6.1, to
resolve compatibility for some Xamarin targets.

Fixes App-vNext#228

Merge pull request App-vNext#225 from reisenberger/v505doco-NoOpPolicy

1.1.0

1.0.0