support official image form

[glensc]

https://docs.docker.com/engine/reference/run/#general-form

the form is:

• IMAGE[:TAG|@DIGEST]

but this does not work:

$ docker-rm ed/gitlab-runner/builds@sha256:82ff0936da09b40393c21cda464312907449aef7069aeebd1ee4fe4938ff2de5
ed/gitlab-runner/builds@sha256:82ff0936da09b40393c21cda464312907449aef7069aeebd1ee4fe4938ff2de5 : no such repository or reference

and afaik the tag could be specified too, but it's just ignored, but visually looking better:

ed/gitlab-runner/builds:some_tag@sha256:82ff0936da09b40393c21cda464312907449aef7069aeebd1ee4fe4938ff2de5

can't find the blog post right now about that.

[DirtyHairy]

Duplicate #5 .