Leo Hemsted 93e631221a use dates rather than datetimes when comparing with bst_date ...

bst_date is a date field. Comparing dates with datetimes in postgres
gets confusing and dangerous. See this example, where a date evaluates
as older than midnight that same day.

```
notification_api=# select '2019-04-01' >= '2019-04-01 00:00';
 ?column?
----------
 f
(1 row)
```

By only using dates everywhere, we reduce the chance of these bugs
happening

2019-09-02 11:56:56 +01:00

..

__init__.py

…

platform_stats_schema.py

…

rest.py

use dates rather than datetimes when comparing with bst_date

2019-09-02 11:56:56 +01:00