Powershell 5 (WMF 5.1) Installer

Powershell 5 is part of WMF 5 and this script downloads and installs WMF 5.1. This script is only for Win7 and Win8.1 machines. Script checks for a couple requirements. First, it checks for .NET 4.5. Then in checks for WMF (Powershell) 4. If both of these are present then script will proceed with installation. Can report using $Powershell5$ and $NoPowershell5$ (failed requirement check).