Retrieving the discrete concentration time series data to calculate the

value for the exceedance plot. Also did some rearranging of the code in
main.js so that code that can run before the siteInfo is done outside of
the promise resolution.
This is a mix of concerns that I'm fine with for now, but we should keep in mind that we can separate markup and procedure more elegantly by using mustache or handlebars templates. My favorite prospect is a convenience wrapper around mustache: http://icanhazjs.com/ @isuftin has been doing some templatification on another project and might have some advice for us.