Set up database change scripts

db/schema.sql is a master copy of the latest schema. db/change/*.sql are scripts that are designed to be run sequentially in order to upgrade a database to the latest version. A database's schema history, including the most-recently-executed change script, can be found in the MetaSchemaHistory table.
Merge branch 'master' of github.com:klossalex/walkingarchive-backend
Add Prices table to schema