migrate Podman to containers/common/libimage

Migrate the Podman code base over to `common/libimage` which replaces
`libpod/image` and a lot of glue code entirely.

Note that I tried to leave bread crumbs for changed tests.

Miscellaneous changes:

 * Some errors yield different messages which required to alter some
   tests.

 * I fixed some pre-existing issues in the code.  Others were marked as
   `//TODO`s to prevent the PR from exploding.

 * The `NamesHistory` of an image is returned as is from the storage.
   Previously, we did some filtering which I think is undesirable.
   Instead we should return the data as stored in the storage.

 * Touched handlers use the ABI interfaces where possible.

 * Local image resolution: previously Podman would match "foo" on
   "myfoo".  This behaviour has been changed and Podman will now
   only match on repository boundaries such that "foo" would match
   "my/foo" but not "myfoo".  I consider the old behaviour to be a
   bug, at the very least an exotic corner case.

 * Futhermore, "foo:none" does *not* resolve to a local image "foo"
   without tag anymore.  It's a hill I am (almost) willing to die on.

 * `image prune` prints the IDs of pruned images.  Previously, in some
   cases, the names were printed instead.  The API clearly states ID,
   so we should stick to it.

 * Compat endpoint image removal with _force_ deletes the entire not
   only the specified tag.

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

vendor/github.com/containers/common/libimage/download.go

@@ -0,0 +1,46 @@
+package libimage
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+
+	"github.com/pkg/errors"
+)
+
+// tmpdir returns a path to a temporary directory.
+func (r *Runtime) tmpdir() string {
+	tmpdir := os.Getenv("TMPDIR")
+	if tmpdir == "" {
+		tmpdir = "/var/tmp"
+	}
+
+	return tmpdir
+}
+
+// downloadFromURL downloads an image in the format "https:/example.com/myimage.tar"
+// and temporarily saves in it $TMPDIR/importxyz, which is deleted after the image is imported
+func (r *Runtime) downloadFromURL(source string) (string, error) {
+	fmt.Printf("Downloading from %q\n", source)
+
+	outFile, err := ioutil.TempFile(r.tmpdir(), "import")
+	if err != nil {
+		return "", errors.Wrap(err, "error creating file")
+	}
+	defer outFile.Close()
+
+	response, err := http.Get(source) // nolint:noctx
+	if err != nil {
+		return "", errors.Wrapf(err, "error downloading %q", source)
+	}
+	defer response.Body.Close()
+
+	_, err = io.Copy(outFile, response.Body)
+	if err != nil {
+		return "", errors.Wrapf(err, "error saving %s to %s", source, outFile.Name())
+	}
+
+	return outFile.Name(), nil
+}