Issue: Batch update contributions

Please consider to add a function to batch update contributions. This would allow us to batch update contributions from minor to major contributions and vice versa, based upon a few criteria:
- more than X characters added.
- less than X characters added/removed
- more than X contributions made within Y minutes

This would allow us to make all minor contributions with more than 1000 characters added major contributions.
It would also allow us to make all major contributions with less than 20 characters and made in a small time frame, to minor contributions.