Add support for referencing images via their 'short sha'

Today if I have an image that is only referenced via a sha - its not easy for me to delete this image. For example

```
container i pull alpine@sha256:8a1f59ffb675680d47db6337b49d22281a139e9d709335b492be023728e11715

container i ls
NAME TAG DIGEST
alpine 8a1f59ffb675680d47db6337...

container i rm alpine:8a1f59ffb675680d47db6337
Error: internalError: "failed to delete one or more images: ["alpine:8a1f59ffb675680d47db6337"]"
```

It is only if I use the `-q` flag with `image ls` is the full sha returned which can be used to perform the delete operation.
```
container i ls -q
alpine@sha256:8a1f59ffb675680d47db6337b49d22281a139e9d709335b492be023728e11715

container i rm alpine@sha256:8a1f59ffb675680d47db6337b49d22281a139e9d709335b492be023728e11715
docker.io/library/alpine@sha256:8a1f59ffb675680d47db6337b49d22281a139e9d709335b492be023728e11715
Reclaimed 650.8 MB in disk space
```

It would make it easier we could use the short sha which is displayed during the output of `image ls` to refer to an image