Add arg-sample code

@mjhubisz

This PR addresses issue #9 by merging the code needed for `arg-sample` into master.

Also, this PR replaces #5.

No, I think it's leftover from some testing I was doing, it is removed now. I was having issues that on some browsers, arg-summarize would run for a long time, and the browser would display a blank screen until arg-summarize completed, then the results would appear. On other browsers, results show up as it is running, and you can watch the scrollbar getting smaller and smaller. Flushing didn't seem to help. I think it might have been a bug in Google Chrome which has since been fixed.