Scraped the CSO data for the past few years

I added a csv file of all the CSO data from the METROPOLITAN WATER RECLAMATION DISTRICT OF GREATER CHICAGO site.  I ended up writing a Ruby scraper (not included, but I can make a pull request for that too if you'd like) to get the data.  You can see that it has start/end time stamps, so should handle any overflows that ran past midnight.  Additionally, any time that CSO duration wasn't available, the data was filled in as if the duration was 59 seconds, which may not be accurate.