Change number of pings to 1

This cuts the test time down from 6s to 2s

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

integration-cli/docker_api_stats_test.go

@@ -90,7 +90,7 @@ func (s *DockerSuite) TestApiStatsNetworkStats(c *check.C) {
 
 	// Retrieve the container address
 	contIP := findContainerIP(c, id, "bridge")
-	numPings := 4
+	numPings := 1
 
 	var preRxPackets uint64
 	var preTxPackets uint64