.net core compatible version published to nuget

[apawsey]

Recompiled and adjusted version compatible with .net 4+ and .net standard 1.3+ published to nuget at https://www.nuget.org/packages/EntityFramework.DbContextScope. If possible I would rather push changes here, but it appears the repository has been abandoned.

[reader-man]

Thanks to @mehdime, @ninety7, @apawsey, for this great library.

[nathan-alden-sr]

Thanks for this, @apawsey. I was about to start doing the same work.