Bindings management for custom render and remove

[RickButler]

This is an extension of #181 and the work of @herkyl

resloves #180

The tests I wrote are the simplest way I could accomplish testing whether downset/upsert were called in custom render functions. I didn't bother keeping a render count because that is covered in:

ampersand-view/test/main.js

Line 43 in f632021

test('event behavior with over-ridden `render` & `remove` fns', function (t) {

I'm back and forth between making this a major/minor SemVer change when this is released. Leaning towards major version bump. I think this qualifies as a breaking change, assuming you had custom render/remove and for whatever reason didn't want to call upsert/downsert for bindings.

Since I made changes here, looking for a +1 from someone else.

[RickButler]

closing this, didn't realize I had the ability to push to @herkyl fork.