Caching form responses

[melissafelch]

It may be helpful to create an autosave primitive for forms.
This could potentially save to the DB or possibly even localstorage. This would be especially helpful if chaining forms (such as while using a formwizard), and allow a user to come back to a form with values already prefilled.

Things to think about:
If we do decide to use a DB for this, how would we generate a UUID to lookup responses? How would cleanup be implemented
Alternatively, if using localstorage (preferred IMO), do we want to invalidate the entry after a certain time?