Format everything with hindent

[tfausak]

This fixes #53.

https://github.com/chrisdone/hindent/commit/8765ef2a0aa09548239643cbc54e86389009acf3

import os
import os.path
import subprocess

for root, directories, files in os.walk('.'):
    if any(root.startswith(os.path.join('.', x)) for x in ['.git', '.stack-work']):
        continue
    for name in files:
        path = os.path.join(root, name)
        if not path.endswith('.hs'):
            continue
        print(path)
        subprocess.check_call(['hindent', path])