Loads config dict from environmental variables (if set):

    * CAN_INTERFACE
    * CAN_CHANNEL
    * CAN_BITRATE

def load_environment_config():
    """
    Loads config dict from environmental variables (if set):

    * CAN_INTERFACE
    * CAN_CHANNEL
    * CAN_BITRATE

    """
    mapper = {
        'interface': 'CAN_INTERFACE',
        'channel': 'CAN_CHANNEL',
        'bitrate': 'CAN_BITRATE',
    }
    return dict(
        (key, os.environ.get(val))
        for key, val in mapper.items()
        if val in os.environ
    )