Replace values in app.config from package metadata

def load_config_from_setup(app):
    """
    Replace values in app.config from package metadata
    """
    # for now, assume project root is one level up
    root = os.path.join(app.confdir, '..')
    setup_script = os.path.join(root, 'setup.py')
    fields = ['--name', '--version', '--url', '--author']
    dist_info_cmd = [sys.executable, setup_script] + fields
    output = subprocess.check_output(
        dist_info_cmd,
        cwd=root,
        universal_newlines=True,
    )
    outputs = output.strip().split('\n')
    project, version, url, author = outputs
    app.config.project = project
    app.config.version = app.config.release = version
    app.config.package_url = url
    app.config.author = app.config.copyright = author