new "image" mount type

Add a new "image" mount type to `--mount`.  The source of the mount is
the name or ID of an image.  The destination is the path inside the
container.  Image mounts further support an optional `rw,readwrite`
parameter which if set to "true" will yield the mount writable inside
the container.  Note that no changes are propagated to the image mount
on the host (which in any case is read only).

Mounts are overlay mounts.  To support read-only overlay mounts, vendor
a non-release version of Buildah.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

vendor/github.com/fsouza/go-dockerclient/container_remove.go

@@ -0,0 +1,39 @@
+package docker
+
+import (
+	"context"
+	"net/http"
+)
+
+// RemoveContainerOptions encapsulates options to remove a container.
+//
+// See https://goo.gl/hL5IPC for more details.
+type RemoveContainerOptions struct {
+	// The ID of the container.
+	ID string `qs:"-"`
+
+	// A flag that indicates whether Docker should remove the volumes
+	// associated to the container.
+	RemoveVolumes bool `qs:"v"`
+
+	// A flag that indicates whether Docker should remove the container
+	// even if it is currently running.
+	Force   bool
+	Context context.Context
+}
+
+// RemoveContainer removes a container, returning an error in case of failure.
+//
+// See https://goo.gl/hL5IPC for more details.
+func (c *Client) RemoveContainer(opts RemoveContainerOptions) error {
+	path := "/containers/" + opts.ID + "?" + queryString(opts)
+	resp, err := c.do(http.MethodDelete, path, doOptions{context: opts.Context})
+	if err != nil {
+		if e, ok := err.(*Error); ok && e.Status == http.StatusNotFound {
+			return &NoSuchContainer{ID: opts.ID}
+		}
+		return err
+	}
+	resp.Body.Close()
+	return nil
+}