Convert htparse to httparser (we lost the parser war)

[NathanFrench]

Now that the parser war is over, let's figure out the best plan of action to replace htparser with httparser.

[mannol]

Great to see this project is being maintained. What's the reason for switch to httparser? Performance, stability, etc?

[NathanFrench]

I'd rather blame obscure code on someone else :)

Silliness aside: I've been going back and forth on this one, last I checked htparser is faster, but probably not as feature-rich as http-parser. Currently I've got bigger fish to fry in this code; doubtful this will be dev/tested anytime soon.