Fix sort order

Author: louiecaulfield

app/models/forem/topic.rb

@@ -42,19 +42,19 @@ def visible
       end
 
       def by_pinned
-        order('forem_topics.pinned DESC').
-        order('forem_topics.id')
+        order('forem_topics.pinned DESC',
+              'forem_topics.id')
       end
 
       def by_most_recent_post
-        order('forem_topics.last_post_at DESC').
-        order('forem_topics.id')
+        order('forem_topics.last_post_at DESC',
+              'forem_topics.id')
       end
 
       def by_pinned_or_most_recent_post
-	order('forem_topics.pinned DESC').
-        order('forem_topics.last_post_at DESC').
-        order('forem_topics.id')
+        order('forem_topics.pinned DESC', 
+              'forem_topics.last_post_at DESC',
+              'forem_topics.id')
       end
 
       def pending_review