steven edits
Merge branch 'master' of https://github.com/stogers/autograder

Conflicts:
	all_submissions/ast2json.py
Merge branch 'master' of https://github.com/stogers/autograder

Conflicts:
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pyanalyze_tweet_sentiment.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pyaverage_sentiments.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pyextract_words.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pyfind_center.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pyfind_centroid.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pyfind_closest_state.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pyget_word_sentiment.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pygroup_tweets_by_hour.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pygroup_tweets_by_state.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pyhas_sentiment.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pymake_sentiment.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pymost_talkative_state.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pysentiment_value.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pytweet_location.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pytweet_time.json
	all_submissions/examplefiles/valid_testing/cs61a-1a-trends.pytweet_words.json
	all_submissions/file_to_ast.py
	all_submissions/iterate_over_submissions.py