Better test cleanup with defer

This fixes a few misuses of `deleteAllContainers()` cleanup
method in integration-cli suite by moving call to the
beginning of the method and guaranteeing their execution
(including panics) with `defer`s.

Also added some forgotten cleanup calls while I'm at it.

Signed-off-by: Ahmet Alp Balkan <ahmetalpbalkan@gmail.com>

integration-cli/docker_cli_nat_test.go

@@ -10,6 +10,7 @@ import (
 
 func TestNetworkNat(t *testing.T) {
 	testRequires(t, SameHostDaemon)
+	defer deleteAllContainers()
 
 	iface, err := net.InterfaceByName("eth0")
 	if err != nil {
@@ -56,7 +57,6 @@ func TestNetworkNat(t *testing.T) {
 	if out, _, err = runCommandWithOutput(killCmd); err != nil {
 		t.Fatalf("failed to kill container: %s, %v", out, err)
 	}
-	deleteAllContainers()
 
 	logDone("network - make sure nat works through the host")
 }