Adds support for .Net runtime 4 in PowerShell by creating a powershell.exe.config file.

EnablePowerShellNet4.ps1

$windowsIdentity = [System.Security.Principal.WindowsIdentity]::GetCurrent()
$windowsPrincipal = New-Object System.Security.Principal.WindowsPrincipal($windowsIdentity)
$adminRole = [System.Security.Principal.WindowsBuiltInRole]::Administrator
if (!($windowsPrincipal.IsInRole($adminRole))) {
 $psi = new-object System.Diagnostics.ProcessStartInfo "PowerShell";
 $psi.Arguments = $myInvocation.MyCommand.Definition;
 $psi.Verb = "runas";
 [System.Diagnostics.Process]::Start($psi);
 exit
}
$psconfig = "{0}\powershell.exe.config" -f $pshome
if(!(Test-Path -Path ($psconfig)))
{
 $config =
@"
<?xml version="1.0"?> 
<configuration> 
    <startup useLegacyV2RuntimeActivationPolicy="true"> 
        <supportedRuntime version="v4.0.30319"/> 
        <supportedRuntime version="v2.0.50727"/> 
    </startup> 
</configuration>
"@
 New-Item -Path $psconfig –type file -value ($config)
}