Add clients to the ATVS Keystroke database.

def add_clients(session, verbose):
  """Add clients to the ATVS Keystroke database."""
  for ctype in ['Genuine', 'Impostor']:
    for cdid in userid_clients:
      cid = ctype + '_%d' % cdid
      if verbose>1: print("  Adding user '%s' of type '%s'..." % (cid, ctype))
      session.add(Client(cid, ctype, cdid))