Create entities

Problem/Motivation

We need entities to hold:

1. Property - a single street address, no unit, one or more tax bill, ie + empty lot
2. Unit - Properties can have more than one unit, have a rent price, have tenants, and paperwork.
3. Room - need to track features of room: appliances, paint, dimensions

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes