1953 distance shared

Hey Anil and Gina, 
I've completed the changes suggested for this insight. These include:

* The insight is now Twitter only, after looking into the hashtags and the style of posts the apps made on other networks, only Twitter was a suitable network.

* Because the insight only supports Twitter I removed the code that checked for duplicate posts on different networks.

* I've changed the language of the copy to be more aimed at encouraging the user to stay active rather than beat records.

* I've added thresholds which provide the user with different feedback depending on the distance that the user shared compared to the previous week. 

* The biggest change to this insight is I have removed the Google chart and now focus on contextual feedback with images related to the feedback being displayed. These are chosen at random so the user should get different feedback. 

* I have edited the InsightTerms class to be more accurate. 

Thanks for all the feedback on this insight, hopefully you enjoy the changes as much as I have. 

![distancesharedv2](https://cloud.githubusercontent.com/assets/4369596/3292412/15cd95cc-f58f-11e3-9da1-fef62ffe3019.PNG)

![distancesharedv2image2](https://cloud.githubusercontent.com/assets/4369596/3292472/b1c00866-f58f-11e3-97e1-88470db1c60b.PNG)

![distancesharedv3image3](https://cloud.githubusercontent.com/assets/4369596/3292477/b4d3c1aa-f58f-11e3-8673-d67f8ee11edf.PNG)