Reify the protocol state when handling connections protocol

[b1conrad]

The specification of the connections protocol (Aries RFC 0160) is given as a state machine, with named states. Our implementation does not record in an entity variable the specific state that a connection-in-progress is at.

I'm proposing that we keep track of the current state in an entity variable. This will facilitate debugging sessions that will occur with other vendors as we work towards interoperability.

[windley]

This is a good idea.