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/setup.go

@@ -74,6 +74,8 @@ func etcdParse(c *caddy.Controller) (*Etcd, bool, error) {
 				switch c.Val() {
 				case "stubzones":
 					stubzones = true
+				case "fallthrough":
+					etc.Fallthrough = true
 				case "debug":
 					etc.Debugging = true
 				case "path":