Add csv/text file reader

[mikefranze]

Should this be another optional input format to the main STAR function? As in you could either pass in the ballots pandas dataframe, summary data, or filename to read data from? Or should we create a seperate function to parse csv into pandas dataframe and pass into main STAR function?

[endolith]

I think it should be a separate function so each can be tested etc. Then maybe a command line interface wrapper that does the whole process? python something.py election.csv?