'Initialize configuration.
This shim will allow for compatibility with the DEFAULT
style of backend configuration which is used by some of the users
of this configuration helper, or by the volume drivers that have
all been forced over to the config_group style.'

def __init__(self, volume_opts, config_group=None):

    self.config_group = config_group
    if config_group:
        self.conf = BackendGroupConfiguration(volume_opts, config_group)
    else:
        self.conf = DefaultGroupConfiguration()
