Update RestartPolicy of container

Add `--restart` flag for `update` command, so we can change restart
policy for a container no matter it's running or stopped.

Signed-off-by: Zhang Wei <zhangwei555@huawei.com>

integration-cli/docker_cli_update_test.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"strings"
+	"time"
+
+	"github.com/docker/docker/pkg/integration/checker"
+	"github.com/go-check/check"
+)
+
+func (s *DockerSuite) TestUpdateRestartPolicy(c *check.C) {
+	out, _ := dockerCmd(c, "run", "-d", "--restart=on-failure:3", "busybox", "sh", "-c", "sleep 1 && false")
+	timeout := 60 * time.Second
+	if daemonPlatform == "windows" {
+		timeout = 100 * time.Second
+	}
+
+	id := strings.TrimSpace(string(out))
+
+	// update restart policy to on-failure:5
+	dockerCmd(c, "update", "--restart=on-failure:5", id)
+
+	err := waitExited(id, timeout)
+	c.Assert(err, checker.IsNil)
+
+	count := inspectField(c, id, "RestartCount")
+	c.Assert(count, checker.Equals, "5")
+
+	maximumRetryCount := inspectField(c, id, "HostConfig.RestartPolicy.MaximumRetryCount")
+	c.Assert(maximumRetryCount, checker.Equals, "5")
+}