Add requirements file to help install dependencies
use double quoted docstrings as required by pep 257

also remove some extra whitespace
use argparse instead of optparse
Merge pull request #10 from yanne/add-requirements-file

Add requirements file to help install dependencies
Merge pull request #11 from yanne/pep-8&pep-257-compatibility

Better compatibility with recommended Python style
Merge pull request #12 from yanne/replace-optparse-with-argparse

use argparse instead of optparse
self.opts is now self.args in app.py