Machine readable status

Hi,

the JSON format is usually something that is supposed to be machine readable, but things like these are rather sad:

    "Up since":  "2020-03-18 10:24",
    "_Up since":  " 4days",
    "Max auth time":  " 2m:19s",
    "Average session time":  " 4m:00s",
    "Max session time":  " 2days",
    "RX":  "10.5 GB",
    "TX":  "91.6 GB"

It would be useful to have simple numbers for those to get these stats into prometheus... our current approach is: ocserv_exporter