mw/kubernetes: remove federation and cidr (#916)

* mw/kubernetes: remove federation and cidr

Remove both as we have a corefile syntax change that handles cidr and
remove federation because that is going to be its own middleware.

* backwards incompat changes

This PR:
* removes cidr from kubernetes (core Corefile feature now)
* removes federation from kubernets (comes back as new middleware)
* [remove autopath - which was already gone, so that already was
  backwards incompat]
* adds `fallthrough` to the *etcd* middleware and makes you enable it.
* Fail on unknown properties
* documentation
* Disable TestHealthCheck as it uses realtime and fails

middleware/etcd/README.md

@@ -23,6 +23,7 @@ If you want to `round robin` A and AAAA responses look at the `loadbalance` midd
 ~~~
 etcd [ZONES...] {
     stubzones
+    fallthrough
     path PATH
     endpoint ENDPOINT...
     upstream ADDRESS...
@@ -33,6 +34,7 @@ etcd [ZONES...] {
 
 * `stubzones` enables the stub zones feature. The stubzone is *only* done in the etcd tree located
     under the *first* zone specified.
+* `fallthrough` If zone matches but no record can be generated, pass request to the next middleware.
 * **PATH** the path inside etcd. Defaults to "/skydns".
 * **ENDPOINT** the etcd endpoints. Defaults to "http://localhost:2397".
 * `upstream` upstream resolvers to be used resolve external names found in etcd (think CNAMEs)