Add retweet count to table display

[dcalvo]

When we return results (and display past results), they should include a retweet column to the right of the compound score. It is sufficient to store the number of retweets when we first logged the tweet; we do not need to update the number in real-time.

[dcalvo]

Compound column should be renamed to "Sentiment"
Retweet column should be to the right of the Sentiment column