Cache json into a suitable location

[IgorTodorovskiIBM]

          There exists Rootfs/var/cache (and a further subdir "zopen" used already by zopen itself ) which would be suitable perhaps?

Having a similar concept to dnf's "--refresh" parameter or "apt-get update" which has to be specified to manually update the JSON cache would be an option familiar to non-zos folks already

Originally posted by @DevonianTeuchter in #30 (comment)