% Deal with meta *list* attributes

For reasons presented meta lists are not working in page templates
(see above, "meta attribute list of hashes").

Suggestion is to always transform them to list of hashes with a
default key (e.g. 'name'). That would be in accordance to "Deal with
author field" above.

Configuration would be:

```
my %list_meta_keys = (
    author => 'name',
    bibliography => 'path',
);
```