Drop .netstandard 1.0

[ipjohnson]

A question was asked by @cnshenj in PR #18 about dropping .netstandard 1.0 support. Microsoft has stopped supporting it so it seems rational to drop support for it as well.

This would allow removal of the compile time diffs added recently to support a netstandard 2.0 only features.

[ipjohnson]

This would also remove the security alert that comes up on the front of the page because of the nuget package.

We found a potential security vulnerability in one of your dependencies.
Only the owner of this repository can see this message.

[ipjohnson]

I've implemented this but I'm going to keep the issue open a while so that people see it

[silkfire]

Maybe time to close this one? :)