Customizable time format

[kevinburke]

I'd like to do HTTP logging. I'd like to log request times at a more granular level than once a second; at a per-millisecond or per-nanosecond level.

I had to reimplement a lot of the format.go code to implement this. It would be nice if this was more customizable! Maybe if I pass in t in the values format, and format the time value myself, it will provide that level of granularity?