Set a single key

    .. note::

        This will strip comments from your config file

def apply(key, value):
    '''
    Set a single key

    .. note::

        This will strip comments from your config file
    '''
    path = __opts__['conf_file']
    if os.path.isdir(path):
        path = os.path.join(path, 'master')
    data = values()
    data[key] = value
    with salt.utils.files.fopen(path, 'w+') as fp_:
        salt.utils.yaml.safe_dump(data, default_flow_style=False)