Disbursement bubble chart refactor

**This branch is not ready to merge yet!**

I've redone the disbursement bubble chart, and it's mostly matching @meiqimichelle's latest comps. Here's what needs to be done still:

- [ ] add the grayed-out initial state with all of the icons
- [ ] figure out what the click state looks like (specifically, where the fund content HTML goes: in a tooltip-style overlay, below the icons?)
- [ ] update `static/data/fund-metadata.json` with the right icon id/names (more on this in a bit)
- [ ] tweak bubble label positions (see the [`tweaks` variable](https://github.com/18F/doi-extractives-data/blob/13a06d806fd02dae3b781e221d317fd43a17ae5c/static/js/bubblegraph2.js#L41-L60))
- [ ] overwrite `bubblechart.js` with `bubblechart2.js` (sorry) and update `_includes/scripts.html` accordingly
- [ ] test the heck out of it