Summarize data

Please, check my code!
I forgot to include some kind of readme.st. To test custom command:
python manage.py summarize [date YYYY-MM-DD] [--nodeletion]
If you pass no parameters it summarizes current date minus 15 days (single day and no a 15-days period)
Why do you need this change? *rbkeys-okapi-web.ini* is supposed to be present, maybe as a symlink to the real rbkeys file (e.g. *rbkeys-okapi-web-dev.ini* or *rbkeys-okapi-web-dev.ini*).