use Condition to block requests on responses
move LocalNode to Configuration::LocalNode
don't allow nil keys in registries
add NodeRegistry

Has special logic to return the local node if asked. There is no need to
set the local node, and its creation is not published.
rename from Zensu to Telecine

All the monitoring stuff was removed a while ago. It makes more sense
to use this repository to build rpc stuff, then build zensu on top of
that.

The rename to Telecine reflects that. Telecine is "the process of
transferring film to video", so it sort of makes sense for an rpc
framework (being mostly concerned with format impedance). Plus it
continues the silly film references!