Add an option to use "native" (millisecond-precision) timestamps.

[wearhere]

For easy use with timestamps derived from JavaScript's Date objects e.g. in Node.js applications.

[wearhere]

@mattbradley besides testing, I'd like to make a note of this in the documentation. Where is that hosted?

[philfreo]

I'd like to make a note of this in the documentation. Where is that hosted?

I belive they are hosted in the gh-pages branch of this repo.