This renames the case_log to lettings_log as everything we've written so
far has been geared towards lettings of social housing so it makes sense to
have the name describe this. This is also a precursor to adding in stuff for
sales logs (whatever shape that takes)
Co-authored-by: James Rose <james@jbpr.net>
* Move storage classes into a dedicated module
* Move configuration classes into a dedicated module
* Refactor configuration service
* Implement configuration via env variables