Use 65534 as the nobody uid
    
    This is part of https://fedoraproject.org/wiki/Changes/RenameNobodyUser.
    Essentially, nfsnobody name is dropped, and nobody is used as the name
    for the "kernel overflow user". The description field is changes to be
    a bit more explanatory. The gid mapping is changed accordingly.
    
    The note about nfsnobody being (uint64_t) -2 is dropped. I don't think
    it was at all true, since nfs-utils has a script that always creates
    "nfsnobody" with uid and gid of 65534.