updated packetmail to use csv.

This is less of an actual MR and more about trying to start a discussion about migrating the input parsing to being handled by the csv module instead of being done by hand. Let me know what you think and I can modify the rest of the parseing functiont to do the same.

Testing for this was:
* call reaper
* call old thresher code to produce harvest.json, renamed to harvest.json.old
* change branch to new thresher code
* called thresher again to produce a new harvest.json file
* ran diff -q between the two files, none were found.

Happy Holidays!