Replace riddler with code that constructs config.json directly

Generated largely from the specified config; small parts taken from `docker image inspect`,
such as the command line.

Renamed some of the yaml keys to match the OCI spec rather than Docker Compose as
we decided they are more readable, no more underscores.

Add some extra functionality
- tmpfs specification
- fully general mount specification
- no new privileges can be specified now

For nostalgic reasons, using engine-api to talk to the docker cli as
we only need an old API version, and it is nice and easy to vendor...

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

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

@@ -0,0 +1,46 @@
+package client
+
+import (
+	"io"
+	"net/http"
+	"net/url"
+
+	"golang.org/x/net/context"
+
+	"github.com/docker/engine-api/types"
+	"github.com/docker/engine-api/types/reference"
+)
+
+// ImagePull requests the docker host to pull an image from a remote registry.
+// It executes the privileged function if the operation is unauthorized
+// and it tries one more time.
+// It's up to the caller to handle the io.ReadCloser and close it properly.
+//
+// FIXME(vdemeester): there is currently used in a few way in docker/docker
+// - if not in trusted content, ref is used to pass the whole reference, and tag is empty
+// - if in trusted content, ref is used to pass the reference name, and tag for the digest
+func (cli *Client) ImagePull(ctx context.Context, ref string, options types.ImagePullOptions) (io.ReadCloser, error) {
+	repository, tag, err := reference.Parse(ref)
+	if err != nil {
+		return nil, err
+	}
+
+	query := url.Values{}
+	query.Set("fromImage", repository)
+	if tag != "" && !options.All {
+		query.Set("tag", tag)
+	}
+
+	resp, err := cli.tryImageCreate(ctx, query, options.RegistryAuth)
+	if resp.statusCode == http.StatusUnauthorized && options.PrivilegeFunc != nil {
+		newAuthHeader, privilegeErr := options.PrivilegeFunc()
+		if privilegeErr != nil {
+			return nil, privilegeErr
+		}
+		resp, err = cli.tryImageCreate(ctx, query, newAuthHeader)
+	}
+	if err != nil {
+		return nil, err
+	}
+	return resp.body, nil
+}