Version associated data by year #3
Description
CBSA data and Census gazetteer data are specific to a year and can only be associated with certain years of HMDA data. We need the ability to download and import other years and somehow version that data.
We could have a year column in the cbsa, county, and state tables, like we do in the hmda table, although that would be problematic: does the year point to the year of data publication or the year of HMDA publication that the data should be associated with. Either one is confusing.
We could also have separate tables for each year's work of data, but that seems super painful for joins.
In order to make this work, we'll need specific importers for each versioned set of data, since the file formats don't stay the same and we'll need to hardcode which datasets pertain to which years of HMDA data. This is a blocker for #4.