Add HN scraper

It fetches all the 'who is hiring' submissions and their comments, keeping
only the top level comments. One problem with the scraper as it stands is
that it can easily get your IP on the temporarily ban list since it
doesn't have any sort of rate limiting. It would probably be wise just to
add a 30 second delay between requests.
Update "who's" to "who is"
Download all threads from April '11 to July '14

I'm 99% sure this includes all the top level comments from all the posts,
but I'll have to double check with the comment counts.

The only one that seems to be missing is the December '11 thread, which
I'll probably just have to write a specific clause for in the scraper.
Luckily, the one comment that resides inside the .json file gives a clue
as to where that thread resides.
Remove dummy data file
Add timeouts to fetch functions