Initial draft for ps module resource

Seems like we could also say that if `source` (aka `download_from`) is not specified, we could download from `package_name` and try to treat the `package_name` as a url since the name might be inferred from the url. Then you could do things like this:

```ruby
  powershell_module 'https://github.com/psget/psget/' do
  end
```