Moving the categories of a blog alone doesn't update the blog's categories location

A blog stores the location of its categories as text (categoriesLocation of Blog.BlogClass). BlogMoveListener updates it when the blog page itself is moved (BLOG-263), but not when the categories space is moved on its own: the blog keeps pointing to the old location.

Steps to reproduce

1. Create a blog MyBlog (its categories are in MyBlog.Categories), with a category
2. Move MyBlog.Categories.WebHome (with its children) to Other.Categories.WebHome
3. Go to the blog and create a post, or manage the categories

Expected: the blog's categories are those of Other.Categories
Actual: the blog's categories location is still MyBlog.Categories: its categories are not listed anymore and new categories are created at the old location

Cause

BlogMoveListener.java:94-96 only handles the rename of a page holding a Blog.BlogClass object. The move of a space used as categoriesLocation (or postsLocation) by a blog is not handled.

The current behaviour is pinned by BlogMoveListenerTest#onEventIgnoresTheCategoriesSpaceMovedAlone (BLOG-269).