Homepage refresh 2.0

You can see all of the remaining issues/enhancements that I have planned here: https://github.com/cid-harvard/atlas-economic-complexity/milestones/Homepage%20Final%20Sprint

The two major ones that could be considered important to finish before we deploy are ~~fixing the homepage search analytics tracking~~ (fixed with search improvements to boot), and ~~changing the carousel images per Marcela's requests~~ (also fixed). But I consider both enhancements/don't want to hold this up any longer/want to get into the practice of deploying more incrementally and often.

The other thing to note is that I've implemented Gulp here to concat/uglify/minify the static resources on the homepage. I'd like to go over those changes with you, @makmanalp, to make sure they make sense and will work on prod.