WIP: Move Repliear to row versioning

[aboodman]

This PR picks up from @tantaman's. There were a lot of little things I wanted to try and easier to build on and use code than go back and forth in reviews.

The main idea in here so far is to change the approach to calculating the pull in a way that for me at least simplifies thinking about it. There are now two steps that run on every pull, regardless of input:

1. Update client_view_entry. This can be done entirely in the DB without round-tripping through application.
2. Calculate patch for client.