Make the GEO label interactive

I've written some additional JS to change the value of a facet slider when that facet is clicked on the GEO label. It'll incrementally cycle through values and when a different facet is clicked the containing div will scroll to the new slider.

I added some additional markup (data-svg-group attribute) to link sliders with the facet SVG groups. I also had to modify the slider event from "slide" to "change" for the sliders because "slide" only triggers on mouse movements while "change" triggers on both mouse movements and when the value is changed programmatically.

You can test this PR by running the following commands with Git Bash when in the repo directory:

git stash
git remote add -f lushc https://github.com/lushc/geolabel-comparison-tool
git fetch lushc
git checkout -b testpr lushc/geolabel-click-to-filter

When you're done you can back to your current work with the following commands:

git checkout master
git stash pop
git branch -D testpr