add allow all hosts by default

set MEDIA_ROOT to match docker-compose.yml ...

otherwise the default of `/etc/netbox/media` is used, which doesn't persist

Adding in support for NAPALM

❇️ Make the default configuration cluster ready ...

This changes the default configuration to be better prepared for
usage with container management platforms, such as Docker Swarm,
Kubernetes or OpenShift.

Closes #27.

✨ Creates a token for admin by default

🐞 Adds most common hostnames to ALLOWED_HOSTS ...

`nginx.netboxdocker.docker` and `netboxdocker.docker` are required
if our ['reception'][1] thing is used to access the container.

Fixes #21

[1]: https://github.com/ninech/reception

Restructured docker-compose.yml