(bug) Use ARGV instead of ARGF

[tkishel]

Do not check ARGF.filename for '-' as (empirically) it always contains '-'

Actually, do not use ARGF as OptionParser.parse! will remove all of its options
from ARGV, leaving only (optional) filenames.

In addition, this guards against STDIN and '-' mismatches,
and handles STDIN in the main data_files loop.

[tkishel]

Without this, Puppet Metrics Viewer waits for STDIN .... forever!

[jarretlavallee]

👍 Looks great. Did you test with the viewer and piping in metrics in the collector?

[tkishel]

I tested ...

json2timeseriesdb --netcat 127.0.0.1 --convert-to influxdb --influx-db archive --pattern "*.json"
json2timeseriesdb --netcat 127.0.0.1 --convert-to influxdb --influx-db archive file.json 
cat file.json | json2timeseriesdb --netcat 127.0.0.1 --convert-to influxdb --influx-db archive
cat file.json | json2timeseriesdb --netcat 127.0.0.1 --convert-to influxdb --influx-db archive -

It consumes all input, and posted it to my running dashboard in docker.

[jarretlavallee]

LGTM!