TweetParser.csvFileToTrainingData() takes in a CSV file that contains tweets
and iterates through the file, one tweet at a time, removing parts of the
tweets that would be bad inputs to MarkovChain (for example, a URL).
This is the class where everything you've worked on thus far comes together!
You can see that we've provided a path to a CSV file full of tweets and the
column from which they can be extracted.