Better communicate .NET 4.7.1 requirement for Windows PowerShell

[SeeminglyScience]

Right now if you try to import the module without net471 or PowerShell core it will throw file not found exceptions. This is because I'm using the net PowerShellStandard library, and the binding redirects weren't included in full framework until net471. A workaround for those who can't use net471 for whatever reason is to drop the netstandard.dll lib in the module directory.