Add view with causes

* Add a causes view using same incidents as main view
* Create new GeoJSON with marker color based on cause
* Add legend identifying causes
Separate purposes

* Add presenter to create objects for views
* Add objects to choose colors for cause markers
* Improve colors of cause markers
Merge pull request #17 from HayleyCAnderson/add-view

Add view with causes

* Create GeoJSON with color sorted by cause
* Add corresponding legend