[3056] Timeline.

Gist: https://gist.github.com/mjelonek92/e1dfe42896c11bbaea4e
Multiline imports should be done like this:
```
from presence_analyzer.utils import (
    jsonify,
    get_data,
    mean,
    group_by_weekday,
    group_start_end_by_weekday
)
```