Code review comment for ~t0rrant/cloud-init:1819966-sysconfig-options

I do not feel comfortable with having a dummy handler for this, I guess
the purpose of the `network` key is exclusive for network interfaces and
network interface interaction. Having a handle_ function is perhaps not
the best choice.

For now this does what is intended, will eventually discuss this with the
cloud-init team and maybe this will be done in some other way.

On a final note, when running tox tests I get several errors/warnings, however:

```
...
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)
```