Not giving config-file to omicron-status returns TypeError

[duncanmmacleod]

Not passing the --config-file option to omicron-status results in a TypeError:

Traceback (most recent call last):
  File "/home/detchar/opt/gwpysoft-2.7/bin/omicron-status", line 172, in <module>
    ok = cp.read(args.config_file)
  File "/home/detchar/opt/gwpysoft-2.7/lib/python2.7/site-packages/backports/configparser/__init__.py", line 702, in read
    for filename in filenames:
TypeError: 'NoneType' object is not iterable

Ideally the command-line parser should be changed to require at least one file, or better error handling should be implemented.