artifact_file does not set owner and group

I have a recipe:

```
artifact_file '/home/myuser/mysql-connector-java.jar' do
  location 'mysql:mysql-connector-java:jar:5.1.31'
  owner 'myuser'
  group 'usergrp'
  action :create
end
```

After it completes I would expect the output file 'mysql-connector-java.jar' to be owned by myuser:usergrp, but since chef-client runs under the 'root' the final file is owned by root:root. 
Alex
