Update Device Initializer for Netbox 2.7 ...

The device database model has changed in Netbox 2.7.
Therefore the initializer code, that was used before, broke.
As a user, you will need to update your devices.yml file as
follows:

- Make sure the rack face is spelled lowercase.

See the diff of this commit for further information how this is meant.

Add missing `break`

Fixed aesthetics.