Update Twitter API resolves #69 #70

Changed the get_twitter_info to get_twitter_image_url and added the twitter and dotenv-rails gems.  I also changed a reference to Dude in the rake task. 

4 Environment variables need to be added to make this work, I used another projects keys and secrets locally.

```
ENV['TWITTER_CONSUMER_KEY']
ENV['TWITTER_CONSUMER_SECRET']
ENV['TWITTER_ACCESS_TOKEN']
ENV['TWITTER_ACCESS_TOKEN_SECRET']
```

There is a rake task already there to update the images `rake twitter:update_avatars`