fixed unit for bandwidth logging

Currently, the proxy logs bandwidth in changing units as the bandwidth scales up (KB->MB->GB). It might be preferable for the proxy operators to have a fixed unit instead. The problems associated with the way it currently works is:

1. If the proxy operator wants to scrape the logs for bandwidth data for use in other programs, the unit keeps changing.
2. Units like GB can cause the values of 1 or 2 to be far less meaningful when the proxy won't see bandwidth in the GB range consistently.

I would suggest fixing the values to KB unit.