Added -Credential option to Invoke-FileFinder and Find-InterestingFile

Added Get-GroupsXML helper to parse groups.xml files
Added -UsePSDrive flag to Get-GptTmpl, Get-NetGPOGroup, Get-DomainPolicy, Find-GPOComputerAdmin, Find-GPOLocation to use temp PSDrives for file parsing

Merge pull request PowerShellEmpire#52 from leechristensen/patch-1

Added missing unattend locations