Ronin cleanup

Hey! A friend just pointed out that you used Ronin to write the new nginx exploit. Good job!

I tried to improve the readability of the exploit in a few ways:

* Use `pack` with descriptive names: `addr.pack(:uint64)`
* Use ronin's `print_info` and `print_error` methods.
* Use `unless` instead of `if not`.
* Use `do ... end` for multi-line blocks.
* 2-space indentation. Sorry, I have been brainwashed into the cult of 2-space indentation ;)

Cherry-pick the commits you like or rewrite them in your style.

Thanks again for using Ronin! :sunglasses: