topics are on model now

[fgregg]

Data is already added. this adjust the code to take advantage of it

closes #406

[derekeder]

@fgregg testing this locally causes an error on the home page. looks like a number of bills don't have routine or topics in the extras field. I added a line to check for this, but the number affected is pretty high

[fgregg]

there shouldn’t be any. should fix this in chicago-council-scrapers

[fgregg]

there aren't any bills in the database without those fields. it's possible that there can be a small window between when the data is scraped and when this script runs. (like a few minutes).

[derekeder]

looks like the topics are there now. might have been a temporary status when i tested on Friday. with the check I added, it won't error if they are missing, so i think we can merge this in.