Enhance fix for published tags (#9), support custom model names too.

When a project uses a custom model, that model name should be used
to query the tags, e.g. a NewsItem model instead of Entry model.
Otherwise, the default Entry model will still be queried for.
Fix using `get_tags` in a project with 2 BlogPage objects.

By passing the `page` and `request` to the included templates,
those templates can use the `blogurl` tag without any problems.
It can detect the current BlogPage where the entry is visible,
so the other possible root can be ignored.
Updated CHANGES with latest fixes.