Move Atomizer after Indexifier in Pipeline

The Indexifier change the given page's output_path so
the Atomizer need to be placed after the Indexifier to
avoid all URL references in the atom feed pointing to the
wrong URL.

Atom Feed URL:
http://escalante.io/news/2013/02/21/why-jbossas-scala.html

Site URL:
http://escalante.io/news/2013/02/21/why-jbossas-scala/