Allow for scraping jurisdictions that aren't in openstates core

[showerst]

I'm planning on turning this into a full PEP later, this is just for taking notes as we write some non-state scrapers.

Things we need to do to allow for scraping any jurisdiction (municipality, county, country, foreign state, etc).

System Wide

• Allow for bills with no bill number. Yuck, maybe we don't relax this and just put in dummies.

State Model changes

• Make fips optional
• Make number of seats on the Chamber object optional. Maybe just make chamber optional entirely

Core Constant Overrides:

Here's where they currently live.

• Bill Type
• Bill Action Type
• Vote Type
• Vote Result

I'm thinking we could let a scraper overwrite these vars but to keep the whole list somewhat organized maybe only as a class variable of the scraper or something? Or call a specific method to append them.

Spitballing:

self.add_bill_action_type("royal-assent", "Royal Assent")
self.add_bill_action_type("mayoral-approval", "Mayoral Approval")