- Add changelog file
- Rename Timelog scope
- Change to between_times to indicate that
arguments are timestamps
- Rename TimelogRefolver aguments to indicate
that they use a TimeType
- Update GraphQL schema and documentation
- Change names in specs

Refactor TimelogResolver

- Support time and date arguments
- Add validation for new arguments
- Refactor specs to cover new validation cases

Allow timelogs field to be null in GroupType