Run idonethis.py as standalone script

I had trouble installing pip, so I tweaked services/idonethis.py to
work as a standalone script. Run: 

    python idonethis.py -f iDoneThis.csv

I also updated `datetime.utcnow()` to `datetime.now()`, since I was getting off-by-one day imports. It also helped to bring in the `convert_to_dayone_date_string(date)` function.