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)
Pycharm sucks. Not PEP 8 compliant by default.
![captura de pantalla 2014-10-04 a la s 12 51 03](https://cloud.githubusercontent.com/assets/53324/4515296/b903aee0-4bb4-11e4-9f48-cc0fc51665d5.png)