* Disable upstream DNS resolver after several tries and fails
* Add tests for upstream fails
* Use an extra flag to disable domains in DNS upstreams
* Fix hashing IPs of nameservers for updates.
Adding --external-ip-map and --dns-resolver-address to up command and shorthand option to global flags.
Refactor get and read config functions with new ConfigInput type.
updated cobra package to latest release.
Added host configurators for Linux, Windows, and macOS.
The host configurator will update the peer system configuration
directing DNS queries according to its capabilities.
Some Linux distributions don't support split (match) DNS or custom ports,
and that will be reported to our management system in another PR
Added DNS update protocol message
Added sync to clients
Update nameserver API with new fields
Added default NS groups
Added new dns-name flag for the management service append to peer DNS label
