Refactor javascript, make geoJson include a pid

[whikloj]

Resolves: #60

The geoJson implementation did not include a pid to allow us to open the popup window. I have refactored the code to include it as a property of the feature.

I have NOT tested this will a hook implementation bringing in outside geoJson. That could break the callback. Best case scenario, you get a map but clicking the markers doesn't open a popup. Worst case scenario, you don't get a map at all

I also refactored the Javascript into a core abstract class IslandoraSimpleMap and then extended that class for Google (IslandoraGoogleSimpleMap) and OpenStreet Maps (IslandoraOSMSimpleMap).

This means each implementation only needs to overwrite the functions to do things in their way. The core initialization and decision making tree is common to both.

It does mean a lot more little functions, but a lot less duplicated javascript.