EmotionAll MVP

Users can choose from a list of trends in our database and see a heat map of the world based on the sentiment of tweets for that particular trend. 
Again, this code that goes to another api should be encapsulated in its own Object.  I'm also not sure why you'd have a `get_sentiment` and a `set_sentiment` method. 

Ruby handles getters and setters as follows:
```ruby
def sentiment
  @sentiment || AlchemyAPI.find ...
end

def sentiment(value)
  @sentiment = value
end
```

If you find yourself, going outside of standard Ruby ways of doing things, it's often a code smell.  You are mixing getting a sentiment from the Alchemy API and the sentiment attribute of a Tweet.