add container image alpine

conf
set container name alp01 image 'alpine'
set container name alp01 network NET01 address '10.0.0.12'
set container network NET01 prefix '10.0.0.0/24'
commit

set container network NET01 prefix '2001:db8::/64'
set container name alp01 network NET01 address '2001:db8::12'
commit

def node_changed(conf, path, key_mangling=None, recursive=False):
    """
    Check if a leaf node was altered. If it has been altered - values has been
    changed, or it was added/removed, we will return the old value. If nothing
    has been changed, None is returned
    """
    from vyos.configdiff import get_config_diff, Diff
    D = get_config_diff(conf, key_mangling)
    # get_child_nodes() will return dict_keys(), mangle this into a list with PEP448
    keys = D.get_child_nodes_diff(path, expand_nodes=Diff.DELETE, recursive=recursive)['delete'].keys()
    return list(keys)