Split peer connect logic to another class (RIPD-711): 

All of the logic for establishing an outbound peer connection including the initial HTTP handshake exchange is moved into a separate class. This allows `PeerImp` to have a strong invariant: All objects that exist represent active peer connections that have already gone through the handshake process.

Reviewers: @nbougalis, @rec 
I think the thing to do is to look at the new code and verify its correctness. The old code could have a bug too.