hand-off

[roger peppe]

I had enough time on the road north to the airport
to produce a spike branch that puts the final foundation piece in
place for the new API server architecture.

I've made a CL here: https://codereview.appspot.com/10684044
(it should have 332-apiserver-factor-out-watchers as
a prereq but I forgot, sorry).

It pretty much works AFAICS. I hope the code is
clear enough that the idea is clear.

I'm looking forward to coming back in two weeks and finding
all the API working!

  cheers,
    rog.