[WIP] K8s update and runtime package changes (#895)

* First commit: outline of K8s runtime package

* Added poller. Added auto-updater into default runtime

* Added build and updated Poller interface

* Added comments and NewRuntime that accepts Options

* DefaultPoller; Runtime options

* First commit to add Kubernetes cruft

* Add comments

* Add micro- prefix to K8s runtime service names

* Get rid of import cycles. Move K8s runtime into main runtime package

* Major refactoring: Poller replaced by Notifier

POller has been replaced by Notifier which returns a channel of events
that can be consumed and acted upon.

* Added runtime configuration options

* K8s runtime is now Kubernetes runtime in dedicated pkg. Naming kung-fu.

* Fix typo in command.

* Fixed typo

* Dont Delete service when runtime stops.

runtime.Stop stops services; no need to double-stop

* Track runtime services

* Parse Unix timestamps properly

* Added deployments into K8s client. Debug logging

runtime/kubernetes/client/api/response.go

@@ -0,0 +1,94 @@
+package api
+
+import (
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/micro/go-micro/util/log"
+)
+
+// Errors ...
+var (
+	ErrNotFound = errors.New("kubernetes: not found")
+	ErrDecode   = errors.New("kubernetes: error decoding")
+	ErrOther    = errors.New("kubernetes: unknown error")
+)
+
+// Status is an object that is returned when a request
+// failed or delete succeeded.
+// type Status struct {
+// 	Kind    string `json:"kind"`
+// 	Status  string `json:"status"`
+// 	Message string `json:"message"`
+// 	Reason  string `json:"reason"`
+// 	Code    int    `json:"code"`
+// }
+
+// Response ...
+type Response struct {
+	res *http.Response
+	err error
+
+	body []byte
+}
+
+// Error returns an error
+func (r *Response) Error() error {
+	return r.err
+}
+
+// StatusCode returns status code for response
+func (r *Response) StatusCode() int {
+	return r.res.StatusCode
+}
+
+// Into decode body into `data`
+func (r *Response) Into(data interface{}) error {
+	if r.err != nil {
+		return r.err
+	}
+
+	defer r.res.Body.Close()
+	decoder := json.NewDecoder(r.res.Body)
+	err := decoder.Decode(&data)
+	if err != nil {
+		return ErrDecode
+	}
+
+	return r.err
+}
+
+func newResponse(res *http.Response, err error) *Response {
+	r := &Response{
+		res: res,
+		err: err,
+	}
+
+	if err != nil {
+		return r
+	}
+
+	if r.res.StatusCode == http.StatusOK ||
+		r.res.StatusCode == http.StatusCreated ||
+		r.res.StatusCode == http.StatusNoContent {
+		// Non error status code
+		return r
+	}
+
+	if r.res.StatusCode == http.StatusNotFound {
+		r.err = ErrNotFound
+		return r
+	}
+
+	log.Logf("kubernetes: request failed with code %v", r.res.StatusCode)
+
+	b, err := ioutil.ReadAll(r.res.Body)
+	if err == nil {
+		log.Log("kubernetes: request failed with body:")
+		log.Log(string(b))
+	}
+	r.err = ErrOther
+	return r
+}