add PythonToScala (#2210)

* [PythonToScala](https://wrobstory.gitbooks.io/python-to-scala/content/) - Rob Story

free-programming-books.md

@@ -2008,6 +2008,7 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Scala By Example](http://www.scala-lang.org/docu/files/ScalaByExample.pdf) - M. Odersky (PDF)
 * [Scala Cookbook: Bonus Chapters](http://examples.oreilly.com/9781449339616-files/Scala_Cookbook_bonus_chapters.pdf) - Alvin Alexander (PDF)
 * [Scala for Perl 5 Programmers](https://github.com/garu/scala-for-perl5-programmers) - Breno G. de Oliveira
+* [PythonToScala](https://wrobstory.gitbooks.io/python-to-scala/content/) - Rob Story
 * [Scala for the Impatient (A1 Scala Level chapters)](http://www.typesafe.com/resources/e-books) - Cay S. Horstmann
 * [Scala School by Twitter](http://twitter.github.io/scala_school/)
 * [Scala Tutorial](http://www.tutorialspoint.com/scala/scala_tutorial.pdf) (PDF)