[Horizon] Re: List of system accounts

If there are alternatives I haven't thought of, please let me know. I'd be amenable to having a file included in the source tree so it isn't hard-coded in *source*, just in a text file, but at this point it seems like six of one and half a dozen of the other. (as in: two solutions but same end result - the Horizon Git tree has to be updated with every adelie-base modification.)