This ticket tracks implementation of the GridFS spec. It introduces a new top level object, GridFSBucket, providing the methods defined in the spec. This new object will co-exist with the existing GridFS class, but not inherit from it.

https://github.com/mongodb/specifications/blob/master/source/gridfs/gridfs-spec.rst

Rebase the AIOHTTPGridFS branch onto this work and use GridFSBucket in its implementation and example.