Add a fqn field to blogs and users (#457)

Fixes #319

plume-models/src/posts.rs

@@ -269,7 +269,7 @@ impl Post {
             post.ap_url = ap_url(&format!(
                 "{}/~/{}/{}/",
                 *BASE_URL,
-                post.get_blog(conn)?.get_fqn(conn),
+                post.get_blog(conn)?.fqn,
                 post.slug
             ));
             let _: Post = post.save_changes(conn)?;
@@ -850,7 +850,7 @@ impl Post {
 
     pub fn url(&self, conn: &Connection) -> Result<String> {
         let blog = self.get_blog(conn)?;
-        Ok(format!("/~/{}/{}", blog.get_fqn(conn), self.slug))
+        Ok(format!("/~/{}/{}", blog.fqn, self.slug))
     }
 
     pub fn cover_url(&self, conn: &Connection) -> Option<String> {