[ci skip] Update Performance Testing guide.

- remove Palmist which is no longer available.
- update link to Query Reviewer.

guides/source/performance_testing.md

@@ -658,9 +658,8 @@ Useful Links
 ### Rails Plugins and Gems
 
 * [Rails Analyzer](http://rails-analyzer.rubyforge.org)
-* [Palmist](http://www.flyingmachinestudios.com/programming/announcing-palmist)
 * [Rails Footnotes](https://github.com/josevalim/rails-footnotes/tree/master)
-* [Query Reviewer](https://github.com/dsboulder/query_reviewer/tree/master)
+* [Query Reviewer](https://github.com/nesquena/query_reviewer)
 * [MiniProfiler](http://www.miniprofiler.com)
 
 ### Generic Tools