Unreadable karton.ini for mwdb when umask is non-standard.

[psrok1]

Configs are not readable when repository was cloned with non-standard umask without +r for others. MWDB drops the worker uid to nobody after forking, so configuration files must be readable for nobody as well.

If it fails to read the configuration, it results in error "Missing S3 configuration"

We should explicitly set mount permissions on volume.