When a blogs was saved, only links of form "/blog/id/write" was
returned, ignoring username. Under a subdomain
("user.blog.site/blog/id/write") this is fine, but it does not work if
a subdomain is not used ("site/blog/id/write"). `HTML::blog_url` should
be called to return the links.
Also, DB::insert_id is called before actually inserting the blogs to get
the new blog's id. This sometimes return a 0, especially when the user
has just deleted a blog. DB::insert_id should be called after the
insert instead.
