v8.0.0

This release:

• updates a bunch of dependencies (#625, #626, #627, #628, #629, #630, #633, #634, #635, #636)
• refactors some internals of the sync() method to allow users to transform local deletes into remote keeps (#640)

This is a major version because it changes one aspect of how remote transformers work. Previously, a remote transformer could return anything for a deleted record, and that record would still be deleted. Now, if a transformer changes a record's _status, it will be respected.