Added feature to pass through arbitrary AppPool properties as a hash

I have added in a way to provide arbitrary application pool properties as a hash.  The key's and values should match what would be used in the command:

"autoStart" => "true", "recycling.periodicRestart.memory" => "512000"

This works well for me as it is straight forward to merge a hash from a data item over top cookbook defaults before passing along to the resource.