add disconnect/reconnect API
Need an API to explicitly connect/disconnect. Initial version: disconnect this machine from the network. Future: disconnect this group from the cloud & other groups.
Why: for debugging, demo, and for voluntary isolation.
Implication: create a "domain" abstraction, which represents a set of logically-equivalent c-service's. e.g.: all the c-services on my machine constitute a domain; all the c-services in my group constitute a domain. Disconnect at domain granularity.