mw/kubernetes: remove kPod and kServices (#969)

Based up on: #939, but redone in a new PR with some cherry-picked
commits:
aacb91ef0b
5dc34247b7

This removes kPod and Kservice and creates []msg.Service from k.findPods
and k.findServices.

Updated few tests which I *think* are correct; they look correct to me.

test/kubernetes_test.go

@@ -214,7 +214,7 @@ var dnsTestCases = []test.Case{
 	},
 	{
 		Qname: "*._not-udp-or-tcp.svc-1-a.test-1.svc.cluster.local.", Qtype: dns.TypeSRV,
-		Rcode: dns.RcodeSuccess,
+		Rcode: dns.RcodeNameError,
 		Ns: []dns.RR{
 			test.SOA("cluster.local.	300	IN	SOA	ns.dns.cluster.local. hostmaster.cluster.local. 1499347823 7200 1800 86400 60"),
 		},