* core: add listening for other protocols
Allow CoreDNS to listen for TLS request coming over port 853. This can
be enabled with `tls://` in the config file.
Implement listening for grps:// as well.
a Corefile like:
~~~
. tls://.:1853 {
whoami
tls
}
~~~
Means we listen on 1853 for tls requests, the `tls` config item allows
configuration for TLS parameters. We *might* be tempted to use Caddy's
Let's Encrypt implementation here.
* Refactor coredns/grpc into CoreDNS
This makes gRPC a first class citizen in CoreDNS. Add defines as being
just another server.
* some cleanups
* unexport the servers
* Move protobuf dir
* Hook up TLS properly
* Fix test
* listen for TLS as well. README updates
* disable test, fix package
* fix test
* Fix tests
* Fix remaining test
* Some tests
* Make the test work
* Add grpc test from #580
* fix crash
* Fix tests
* Close conn
* README cleanups
* README
* link RFC
