New resources and fix for scriptblock parsing

[devblackops]

Adds the following resources:

• DnsHost - Test DNS resolution to a host
• Folder - Test if a folder exists
• Interface - Test a local network interface
• LocalGroup - Test if a local group exists
• Package - Test for installed package

This also makes a small change to Get-PoshspecParam that fixes a bug I was seeing when the scriptblock implementing the test included strings like the code below:

$expression = {Get-CimInstance -ClassName Win32_Group -Filter "Name = '$Target'"}

[cdhunt]

I debated doing a "Folder" function since "File" works for folders as well, but that makes it clear what you are testing. I think it would also be useful to be able to test if a specific users is or isn't part of a local group. Thank you for adding additional scriptblock processing logic.