Better exclude

[mrwulf]

I added a "better" way to exclude changes (and more importantly deletes!) from being propagated. There's a simple test to show how a key gets clobbered unless it is excluded. I don't think it's obvious from the documentation that after each change (+ quiescence period) the ENTIRE kv tree is traversed. I'll file that away as a future enhancement once I'm a little more go-competent.

[mrwulf]

So... why didn't this get merged during the last release?

[hashicorp-cla]

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