Move engine-api client package

This moves the engine-api client package to `/docker/docker/client`.

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

client/swarm_update.go

@@ -0,0 +1,21 @@
+package client
+
+import (
+	"fmt"
+	"net/url"
+	"strconv"
+
+	"github.com/docker/docker/api/types/swarm"
+	"golang.org/x/net/context"
+)
+
+// SwarmUpdate updates the Swarm.
+func (cli *Client) SwarmUpdate(ctx context.Context, version swarm.Version, swarm swarm.Spec, flags swarm.UpdateFlags) error {
+	query := url.Values{}
+	query.Set("version", strconv.FormatUint(version.Index, 10))
+	query.Set("rotateWorkerToken", fmt.Sprintf("%v", flags.RotateWorkerToken))
+	query.Set("rotateManagerToken", fmt.Sprintf("%v", flags.RotateManagerToken))
+	resp, err := cli.post(ctx, "/swarm/update", query, swarm, nil)
+	ensureReaderClosed(resp)
+	return err
+}