Video sprint18 video page redesign

This is for video page redesign, and it has the following changes:
- /includes/ImagePage.php->view() code abstractions to protected functions, so it can be overwritten
- RelatedPages refactor to support the feature on new video page
- New DB calls to generate "appears in local wiki"
- New DB and external calls to generate "appears in other wikis"
- Video Page design insertions