Fix dynamic map resize

[Crista2019]

The map does not resize itself when the size of the browser screen changes. We have code in place to redraw the svg when a resize occurs, but we haven't yet implemented a surrounding container whose width we can base the resize off of. This shouldn't be too hard, but we tabled this issue until we finish our MVP #44

[Crista2019]

This might not be an issue since we want the map to be significantly smaller than the outer framework (i.e. scale down map so it can be viewable when the user moves the year slider, see issue #67 )