TOOLS: sss_groupshow did not work
    
    sss_groupshow used shortname to search
    in sysdb database. We have to u e sysdb_fqname
    (aka internal_fqname) format for all sysdb
    oprations.
    
    Resolves:
    https://fedorahosted.org/sssd/ticket/3175
    
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>