Handle primary IPs on devices and VMs

Update VM Initializer for Netbox 2.7 ...

The vm 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 virtual_machines.yml
file as follows:

- Make sure the status is spelled lowercase.

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

Reformat initializers and add some IPv6 examples

Fixed further requirements.

Fixed aesthetics.

Added more startup_scripts and initializers examples.