Removes Paloma

I spoke with Derek and Josh and they seemed extremely weary about using the Paloma Gem. With that in mind and the fact that our application will likely be modified by other developers in the future, I decided to re-implement all of the functionality without the paloma gem. I reintroduced the use of the script tag, only this time I use a conditional to ensure it is only executed if @viz_data is passed from the back end. This means we no longer have to pass in a value for @viz_data each time.

This pull request also implements all of the improvements I made in my previous (cancelled) pull request. 

All tests are green!

@melissa-mccoy @wh1tney