dotnet core version of FeatureSwitcher

[Stefan B\u+00F6ther]

I really want this lib for the .Net Core Framework.
https://www.microsoft.com/net/core

The best would be that it have very few dependencies to other libs and following the .NET Standard Platform Version 1.6
https://github.com/dotnet/corefx/blob/master/Documentation/architecture/net-platform-standard.md

[Max Malook]

At a quick look on the document your referenced, the library should be able to target netstandard1.0.
Thanks again for the #11

[Max Malook]

Closed by #17