post votes: let gold users use upvote:self, downvote:self metatags.

* Let gold users use upvote:self, downvote:self metatags to search for
  their own votes.
* Don't let mods use upvote:<user>, downvote:<user> metatags to see
  votes by other users. Only let admins see other users' votes.
* Add vote count to profile page.

app/logical/post_query_builder.rb

@@ -473,14 +473,12 @@ class PostQueryBuilder
     end
 
     if q[:upvote].present?
-      user_id = q[:upvote]
-      post_ids = PostVote.where(:user_id => user_id).where("score > 0").limit(400).pluck(:post_id)
+      post_ids = PostVote.where(user: q[:upvote]).where("score > 0").select(:post_id)
       relation = relation.where("posts.id": post_ids)
     end
 
     if q[:downvote].present?
-      user_id = q[:downvote]
-      post_ids = PostVote.where(:user_id => user_id).where("score < 0").limit(400).pluck(:post_id)
+      post_ids = PostVote.where(user: q[:downvote]).where("score < 0").select(:post_id)
       relation = relation.where("posts.id": post_ids)
     end