Replace removed singularity command
Replace removed singularity command

This commit replaces use of the `singularity check` command with `singularity
inspect`. The `check` command was removed in Singularity 3.0 (though this
wasn't mentioned in the project's change log).

Strictly speaking, the `inspect` command does less than the original `check`
command--the former merely parses the image and display its metadata whereas
the latter also applies security heuristics. However, it would appear that Kive
was using the `check` command to validate that an uploaded file was in fact a
Singularity image, and not depending on `check`'s other features.

(cherry picked from commit e9db204c868e8115c4f6c10b16b991cff4e5eb36)

cfe-lab/Kive,cfe-lab/Kive,cfe-lab/Kive,cfe-lab/Kive,cfe-lab/Kive