CameronDiver

Add ability to control host discoverability with a configuration variable

3

Using a `BALENA_HOST_DISCOVERABILITY` variable we should allow the user to toggle avahi on/off, with the default being on.

Looking at logs of the supervisor for debugging, seeing an image ID removal doesn't really help at all, because that ID isn't easy to use to go to an actual...

Expose the dnsServers config.json field over environment variable

2

The ability to specificy additional dns servers should be possible through the `RESIN_ADDITIONAL_DNS_SERVERS` variable. [Front conversations](https://app.frontapp.com/open/top_cr6b)