Add vendoring

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

vendor/github.com/docker/engine-api/client/container_diff.go

@@ -0,0 +1,23 @@
+package client
+
+import (
+	"encoding/json"
+	"net/url"
+
+	"github.com/docker/engine-api/types"
+	"golang.org/x/net/context"
+)
+
+// ContainerDiff shows differences in a container filesystem since it was started.
+func (cli *Client) ContainerDiff(ctx context.Context, containerID string) ([]types.ContainerChange, error) {
+	var changes []types.ContainerChange
+
+	serverResp, err := cli.get(ctx, "/containers/"+containerID+"/changes", url.Values{}, nil)
+	if err != nil {
+		return changes, err
+	}
+
+	err = json.NewDecoder(serverResp.body).Decode(&changes)
+	ensureReaderClosed(serverResp)
+	return changes, err
+}