Allow for autosaves to act through /bulkSave

- Idea 1: `{deep: 'bulk'}`
- Idea 2: `{bulk: true}`
- Idea 3: This is the only way that deep autosaves work now. Sure would be a heck of a lot easier than the current `deep` approach. Has a very unlikely edge case where the root model being autosaved isn't readable by the user, but if that's true then how did the user load it in the first place to initiate bulk saves?

Dependent upon #413 to setup watchers on the result of the bulk save "pending state".