Disable older version of NuGet provider to be installed or loaded on PowerShell Core from repo.

[SteveL-MSFT]

From @jianyunt on July 13, 2016 20:48

As NuGet provider is a part of PowerShell Core now, it no longer requires to be bootstrapped. However, we need to disable any older version of NuGet provider to be installed or used on Core because they simply won't work on PowerShell Core alpha version..

Steps to reproduce

find-packageprovider
install-packageprovider -name NuGet -version 2.8.5.205 -force
install-module xjea

Expected behavior

Error out if people are trying load any older version of NuGet provider

Actual behavior

not sure yet

Environment data

PowerShell

Copied from original issue: PowerShell/PowerShell#1355