api and JS to update project funding percentages automatically.

paired on the JS with my buddy @zackferraro.
Thinking about this a bit more, I don't know that `Accounts` are relevant to end users. When we start re-implementing the views to be API-driven, I think we'd only care about `Projects`. That leads me to think that the percentage should be within a `project` endpoint, but that sort of rewrite is probably out of scope for this pull request.