Fix extra param in DB query

lib/search.rb

@@ -27,7 +27,7 @@ def search(params)
 end
 
 def search_threads(db, query, username, sort, offset)
-  db[<<-SQL, query, username, username, String.new, offset]
+  db[<<-SQL, query, username, username, offset]
     SELECT
       threads.*
     FROM threads