wip: kv rest api work

+ Range actions (get and delete)
+ Counter deletions

Take a look at any new TODOs as they most likely contain questions that I’ll probably just end up emailing the list about anyway :)
I was going off of this design document from hack week back in July: https://docs.google.com/document/d/1JbplJxyCw82MFOXCZOyKCwe_heAjaub_WjBuUsS3lVs/edit#heading=h.iqw89he4ghl1

I will put in a TODO for that and the stuff you mention about the range info in the request headers (I had read about that as well when I was doing that initial research about rest APIs that conform to Angular/React/EmberJS). In the interest of simplicity of the initial portion I decided to leave that out.