add VoteCounts to Chicago scraper

[Derek Eder]

We are collecting votes for Chicago now, but for convenience, we should be summarizing them for each bill using the VoteCount model: https://github.com/opencivicdata/python-opencivicdata/blob/master/opencivicdata/legislative/models/vote.py#L67

[Forest Gregg]

@derekeder this is in the DB now.