Accounting-suitable logging

[stuartpb]

Talked with @tjfontaine about this at the Node on the Road office hours - he suggested creating a socket that's passed to the TLS connection constructor that pipes to a transform that simply counts bytes and logs them.

However, the tricky bit is tying the TLS-level logging to the HTTP-level logging, which he wasn't sure about (beyond diving into the undocumented private bits of the Socket interface).