Correcting hiera paths

Created by: solsglasses

I noticed a few paths related to hiera are incorrect. Let me know what you think.

1. Default yaml backend was wrong. The value is configurable, so I was able to workaround it by specifying my own path.
2. Location of hiera.yaml is wrong. This value is not configurable, so I was working around it by creating a symlink from wrong file -> correct file.