Custom auto-save feature

[vnazarenko]

Is your feature request related to a problem? Please describe.
I use custom versioning in model, so it can't be just saved with .save1. It should be save through custom method like: .update_by_user(user, attributes).

Describe the solution you'd like
I want to have posibility to customise auto-save process. Implement it by my self.

Describe alternatives you've considered
Right now i could monkey-patch aasm to archive that.