Remove the special config file

First of all the `README.md` was quite good when I started to use the netapp types. But it didn't really explained what to put in the device configuration.

When I found out about the syntax of the device configf file I was wondering if the second `netapp.yml` file is actually needed because the username and password can be part of the connection url.

So here is an attempt to get rid of it. If backward compatibility is an issue we can detect malformed urls and load the `netapp.yml` file only if present. The code right now will just trigger an exception.