automated deltas

[WolframHempel]

Use the algorithm that's used to find tree conflicts within merges ( #82 ) to automatically check objects provided by record.set( obj ) against the previous version to establish if only a path within the record has changed. If so, send a patch rather than an update

[yasserf]

Since we didn't do tree conflicts as a provided merge strategy this will have to be postponed until we add it in.