Added command-line utility which reformats NEWS into standart debian changelog

I didn't know what should be in the `-- maintainer name <email address>[two spaces]  date` lines, so it's value is configurable as a global variable in the script.

This script is one shot — after reformatting, if changelog is OK, I suppose we should use something like `dch -i -c CHANGELOG` to update information about future releases.

Feel free to critique, because it is my first program in `hy` :)
Might be more pythonic to do that with `yield` ?