Track events: create, save, delete, widget list, map modal list

Per [chore 69798352](https://www.pivotaltracker.com/story/show/69798352).

Now has separate functions to encapsulate the above events (several of which are the same except for names to distinguish what kind of event it is).  In order to capture list load times, the code now injects Javascript event handlers, which respond by adding `list-loaded` to the `ul` class that is loading.