add config

config/source/memory/watcher.go

@@ -0,0 +1,23 @@
+package memory
+
+import (
+	"github.com/micro/go-micro/config/source"
+)
+
+type watcher struct {
+	Id      string
+	Updates chan *source.ChangeSet
+	Source  *memory
+}
+
+func (w *watcher) Next() (*source.ChangeSet, error) {
+	cs := <-w.Updates
+	return cs, nil
+}
+
+func (w *watcher) Stop() error {
+	w.Source.Lock()
+	delete(w.Source.Watchers, w.Id)
+	w.Source.Unlock()
+	return nil
+}