Export contents of devices table in Kismet DB to json file.

usage: kismet_log_devices_to_json [-h] [--in INFILE] [--out OUTFILE]
                                  [--start-time STARTTIME]
                                  [--min-signal MINSIGNAL]

optional arguments:
  -h, --help             show this help message and exit
  --in INFILE            Input (.kismet) file
  --out OUTFILE          Output filename (optional). If omitted, logs multi-
                         line and indented (human-readable) to stdout.
  --start-time STARTTIME Only list devices seen after given time
  --min-signal MINSIGNAL Only list devices with a best signal higher than min-signal