Removing the check for administrator rights from the script that sends keystrokes to Hyper-V.

Because Packer has already verified that we are running with at least Hyper-V administrator rights this should
be safe. Having the requirement for administrator rights in the script means that you still need to be an
administrator if you want to use packer to build Hyper-V images with a configuration that requires you to
send keystrokes to the MV, say when building a Linux box.

common/powershell/hyperv/hyperv.go

@@ -806,7 +806,6 @@ func TypeScanCodes(vmName string, scanCodes string) error {
 	var script = `
 param([string]$vmName, [string]$scanCodes)
 	#Requires -Version 3
-	#Requires -RunAsAdministrator
 
 	function Get-VMConsole
 	{