Move WoW db config out to a YAML file.

[toolness]

We need to be able to load/update the WoW database from our containerized DB updater at JustFixNYC/nycdb-k8s-loader#22. One simple way to do this is by putting all our database configuration into a YAML file, similar to what NYCDB is already doing.

This PR moves the names of all the NYCDB dataset dependencies and the SQL filenames into a new who-owns-what.yml file. It also makes the following changes:

• We no longer load the pluto_17v1 dataset; it seems this was entirely superseded by pluto_18v1, although I should check with @sraby to make sure this is OK.

• The --update option for dbtool.py builddb now wipes all nycdb data instead of just a subset of tables. This simplified the structure of the YAML and seems OK since nycdb-k8s-loader will now be responsible for updating WoW in a more rigorous manner. If we really want to add this feature back in, we might want to add a separate flag that allows the user to manually specify which datasets to refresh.

• It automatically figures out what the tables in a dataset are by consulting the nycdb module.

[sraby]

Checked: we only use pluto_18v1 so removing those dependent datasets is great!