Run as iocuser:iocgroup and not as root:root

Added CAP_SYS_NICE and CAP_IPC_LOCK so that chrt works

The problem with running as root is that root is not allowed to write to the nonvolatile NFS share. Running as iocuser causes some problems when trying to run a realtime IOC. It is not exactly clear what those problems are (hopefully the added capabilities solves at least some of them) but the autosave functionality (i.e. being able to write to the nonvolatile share) is more important