Add response time information

[danielthatcher]

Currently information about status codes and response lengths is shown. Timing information could also be useful when using AutoRepeater for certain types of testing (original response time, new response time, response time diff).

[justinmoore]

This should be doable, but I'm unsure if there's space to fit it into the log viewer. I'll open another issue for the support changing the columns shown in the log viewer to allow a larger variety of values to be shown in the viewer without it getting too cramped.

[justinmoore]

In the interim while I implement this functionality, it looks like Logger++ should enable you to sort requests based on the response time.