Fix polygon map bounds

[mjmdavis]

Leaflet needs to know the size of the viewport in order to calculate the zoom level for displaying geojson content.
In order to resize gracefully, fitBounds needs to be called each time the size of the map is changed.

By moving the fitBounds call into update we can ensure that the geojson will always fit inside the viewport of the map.
Fixes #28

[mjmdavis]

Thinking about it, this could be annoying when you want to stay zoomed into a specific spot...

[mjmdavis]

@gnestor @blink1073 can someone cast an eye over this?

[gnestor]

@mjmdavis Thanks!! I tried it out and there is an improvement when rendering an (polygon) output in a notebook. I don't see any different when rendering a GeoJSON document.

Thinking about it, this could be annoying when you want to stay zoomed into a specific spot...

Can you elaborate?

[mjmdavis]

@gnestor The issue could arise when the user wants to stay zoomed into a specific spot, then resizes. Their zoom would be reset and they could lose their place. I think we can probably ignore this for now. If it's that important, a user could only render the section of geojson that they care about.

[mjmdavis]

I have a wip with a 'zoom to bounds' button that breaks the build for some reason.

[mjmdavis]

@gnestor I feel like this is ready to merge. It fixes the bounds zoom of geojson inside notebooks, and this is super annoying for my team at work. Let me know if there is anything else I should change.

I'll working on #114.

[gnestor]

Ok, thanks @mjmdavis!