Hotfix/2271 export csv data quality issues

@aronasorman.

We didn't changed the queryset for `login_logs` that uses `UserLogSummary` because this class is synced in central server.

For now, narrowing out date range in less than a month to generate **CSV report** causes `total_hours` column deferent from **web view** `Login Time`.
Reason:
1. Date range of `UserLogSummary` is at least one month.

**Recommendation:**
We will use `UserLog` instead of `UserLogSummary`.
 Problems in using `UserLog`:
1. Not synced in central server
2. We cannot replicate the issue using `generaterealdata` because `generaterealdata` generates exercise into a single `UserLog`