Use Case: Use Jawn and a "Database Tracker" to replicate db Updates

This is a sample use case based on conversations with Open Data Philly. See

[Jawn Use Case - Replicate db Updates.pdf](https://github.com/CfABrigadePhiladelphia/jawn/files/262145/Jawn.Use.Case.-.Replicate.db.Updates.pdf)

Janelle tells the database tracker to commit her changes from db1 (see #41)
The database tracker detects the changes (see #43) and writes the changes to jawn1 (see #46)
Jawn replicates the changes into jawn2
The database tracker on the other end applies the changes to db2