Harmonize / across all name-related commands

Docker-DCO-1.1-Signed-off-by: Djibril Koné <kone.djibril@gmail.com> (github: enokd)

Harmonize / across all name-related commands

Docker-DCO-1.1-Signed-off-by: Djibril Koné <kone.djibril@gmail.com> (github: enokd)

Harmonize / across all name-related commands:Return an error when repeated /

Docker-DCO-1.1-Signed-off-by: Djibril Koné <kone.djibril@gmail.com> (github: enokd)
Harmonize / across all name-related commands/Validate images names

Docker-DCO-1.1-Signed-off-by: Djibril Koné <kone.djibril@gmail.com> (github: enokd)
Merge pull request #4751 from enokd/master

Fixes #3369 Repeated slash-'/' characters; harmonize across all name-related commands