Blog WS for getting entries is not returning all the expected data

We need to fix the core_blog_get_entries WS to retrieve;

• Missing associations to display links to courses/activities and to fix/improve the course/activities blog detection/linking from courses/activities
• Obtain the URL and title of the external blog (content field for external is just an id). This could be added to the exporter
• User fullname and picture to avoid getting every uper profile.