refactor stats to not use internal data structures

- refactor to make it easier to split the api in the future
 - addition to check the existing test case and make sure it contains
   some expected output

Signed-off-by: Morgan Bauer <mbauer@us.ibm.com>

integration-cli/docker_cli_stats_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"os/exec"
 	"strings"
 	"time"
@@ -15,18 +16,28 @@ func (s *DockerSuite) TestCliStatsNoStream(c *check.C) {
 	c.Assert(waitRun(id), check.IsNil)
 
 	statsCmd := exec.Command(dockerBinary, "stats", "--no-stream", id)
-	chErr := make(chan error)
+	type output struct {
+		out []byte
+		err error
+	}
+
+	ch := make(chan output)
 	go func() {
-		chErr <- statsCmd.Run()
+		out, err := statsCmd.Output()
+		ch <- output{out, err}
 	}()
 
 	select {
-	case err := <-chErr:
-		if err != nil {
-			c.Fatalf("Error running stats: %v", err)
+	case outerr := <-ch:
+		if outerr.err != nil {
+			c.Fatalf("Error running stats: %v", outerr.err)
+		}
+		if !bytes.Contains(outerr.out, []byte(id)) {
+			c.Fatalf("running container wasn't present in output")
 		}
 	case <-time.After(3 * time.Second):
 		statsCmd.Process.Kill()
 		c.Fatalf("stats did not return immediately when not streaming")
 	}
+
 }