go/mirko: move kubernetes clientset state to singleton

We want to access the clientset (or at least check the fact that we're
in a cluster) outside of the Mirko object lifecycle.

In reality, this should _probably_ be moved outside of the Mirko library
and get a better API than this (ie. one that returns complete
information about the state of being in production/dev/...).

Change-Id: I86444477e0306a39a1611207855127a7b963603e
diff --git a/go/mirko/mirko.go b/go/mirko/mirko.go
index f4c45eb..339e70c 100644
--- a/go/mirko/mirko.go
+++ b/go/mirko/mirko.go
@@ -130,7 +130,7 @@
 		http.Redirect(w, r, "/debug/status", http.StatusSeeOther)
 	})
 
-	m.kubernetesConnect()
+	m.kubernetesCS = KubernetesClient()
 
 	debugParts := strings.Split(flagDebugAddress, ":")
 	debugPort := debugParts[len(debugParts)-1]