incomplete validation of SLURM files

[reschke]

RFC 8416 requires any dviation from the format to be treated as error (see https://tools.ietf.org/html/rfc8416#section-3.1).

However, various deviations, such as

• extra JSON members
• missing slumVersion
• slurmVersion not set to "1"

apparently are ignored.

Related to that: it would be nice if processing of Slurm resources would cause something to be written to the log above "debug" level, consistent with the processing of the validated cache.