Add collision data to map

* Get data from SODA API using HTTParty
* Clean data and enter into database
* Add markers representing data to map using MapBoxJS
* Move map directly into home show page
* Improve use of MapBox gem
I feel like check doesn't really explain what your trying to do here.

I would like it better if `cyclist_casualities` just returned a number. Then maybe there is a predicate method that takes advantage of that.

Likewise for pedestrian_casualities