broken when no remote client

[hb020]

when no remote client is given, fio fails to start.

realtime_back.py, line 14

    if client:
        remote_server = "--client=" + client
    fio_process = subprocess.Popen(['fio', remote_server, '--minimal', '--eta=0', '--status-interval=1', path], stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True, preexec_fn=os.setpgrp)

should be something like:

    if client:
        remote_server = "--client=" + client
        fio_process = subprocess.Popen(['fio', remote_server, '--minimal', '--eta=0', '--status-interval=1', path], stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True, preexec_fn=os.setpgrp)
    else:
        fio_process = subprocess.Popen(['fio', '--minimal', '--eta=0', '--status-interval=1', path], stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True, preexec_fn=os.setpgrp)

fresh install of Ubuntu 18.04 LTS, with fio (3.1-1)

That version of fio seems to work. It is not tested all the way, but maybe it is time to adapt the readme.md.