Internal transport delay computation

[brunolnetto]

According to definition below, the difference total-time - response-time refers to inner-transport delay. May we compute this interval on morgan-json?

:response-time[digits]
The time between the request coming into morgan and when the response headers are written, in milliseconds.

:total-time[digits]
The time between the request coming into morgan and when the response has finished being written out to the connection, in milliseconds.