Improves discovery of usable nuget.exe binary (#558)

Includes minimum required version to the checks in Program Files and User AppData Local folders. This prevents issues with outdated nuget.exe binaries in Program Files occluding newer versions in User's AppData folders or locations on the PATH.

Author: bwright86

src/PowerShellGet/private/functions/Install-NuGetClientBinaries.ps1

@@ -93,11 +93,13 @@ function Install-NuGetClientBinaries
             $applocalDataExePath = Microsoft.PowerShell.Management\Join-Path -Path $script:PSGetAppLocalPath -ChildPath $script:NuGetExeName
 
             # Check if NuGet.exe is available under one of the predefined PowerShellGet locations under ProgramData or LocalAppData
-            if(Microsoft.PowerShell.Management\Test-Path -Path $programDataExePath)
+            if( (Microsoft.PowerShell.Management\Test-Path -Path $programDataExePath) -and 
+                ($programDataExePath | Microsoft.PowerShell.Core\Get-Command).Version -ge $script:NuGetExeMinRequiredVersion )
             {
                 $NugetExePath = $programDataExePath
             }
-            elseif(Microsoft.PowerShell.Management\Test-Path -Path $applocalDataExePath)
+            elseif( (Microsoft.PowerShell.Management\Test-Path -Path $applocalDataExePath) -and 
+                ($applocalDataExePath | Microsoft.PowerShell.Core\Get-Command).Version -ge $script:NuGetExeMinRequiredVersion )
             {
                 $NugetExePath = $applocalDataExePath
             }
@@ -344,4 +346,4 @@ function Install-NuGetClientBinaries
                     -CallerPSCmdlet $CallerPSCmdlet `
                     -ErrorCategory InvalidOperation
     }
-}
+}