Workaround an insufficient auth scope requested by gitlab registry.
When deleting tags from gitlab registry, the registry requests a bearer token with scope "registry:{PROJECT}:delete". However, the auth server refuses to hand out tokens with ":delete".
This adds an option --gitlab-auth-scope-fix that instructs registry-cli to turn a request for ":delete" tokens into a request for ":*" tokens.
Addresses: joe/schedules#2