Enrich data model

Had to enrich the data model a bit so that we track:

* jurisdiction: where the election happens
* type: a more limited list of possible types, i.e. `general`, `by-election`, `municipal`
* scope: for municipal elections, there's a more limited list of possible subtypes, e.g. `hamlets`
* division: if it's a by-election, the name of the electoral district
* notes: any additional notes on the election