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/hosts/setup.go

@@ -79,6 +79,8 @@ func hostsParse(c *caddy.Controller) (Hosts, error) {
 					continue
 				}
 				return h, c.ArgErr()
+			default:
+				return h, c.Errf("unknown property '%s'", c.Val())
 			}
 		}
 	}