added module hr_worked_days_from_timesheet

`ts.date_from` will return a date string in the default Odoo date format.

You may want to format the date according to the user's context.

You can get the user's date format like this. (I wish there were a dedicated function for this.)
```python
lang_pool = self.pool['res.lang']
user_pool = self.pool['res.users']
code = user_pool.context_get(cr, uid).get('lang', 'en_US')
lang_id = lang_pool.search(cr, uid, [('code', '=', code)], context=context)
date_format = lang_pool.read(cr, uid, lang_id, ['date_format'], context=context)[0]['date_format']
date_from = datetime.strptime(
    ts.date_from,
    DEFAULT_SERVER_DATE_FORMAT
).strftime(date_format)
```