Provide full list of tags with missing manifests instead of showing error or "?" next to them #124
Description
When using docker-distribution on Red Hat Enterprise Linux as a private registry, the deletion of manifests associated with a tag leaves a dangling tag directory in the "_manifests/tags/" directory. this causes the registry to return the tag when queried, but will return a "Manifest unknown" error if you try to do anything with it.
Because of this, after deleting multiple tags of an image through the Joxit UI, you'll get a "Manifest for IMAGE:TAG not found" error in red and "?" characters where its info should be. All you see is the name of the tag. This is not a Joxit bug per say, but there's something Joxit could do to help.
Instead of listing the broken tags in the UI, sometimes over multiple pages, there could be a separate list (perhaps with a clear WARNING icon somewhere), showing all the broken tags by name so we can more easily have the dangling directories manually deleted by a sysadmin on the docker-distribution server (i.e. rm -rf /var/lib/registry/docker/registry/v2/repositories/${IMAGE}/_manifests/tags/${TAG}), which will instantly fix the issue.