Add Upstream API to regular API

[squaremo]

At present, there are a small number of methods in the Upstream API that are not in the flux API. These are methods that can be called via RPC from an upstream (i.e., Weave Cloud) connection, but not via HTTP (e.g., not by fluxctl).

In the course of separating the Upstream part of the daemon out into weaveworks/flux-adapter, these will have to move into the public API, since flux-adapter runs in a sidecar, and uses HTTP (via http/client) rather than having in-process access to the daemon.

I believe the upstream methods can just be added to the v11 Server interface, and the Upstream interface abandoned from now on.