* Added Portuguese and Italian Translations.

Added Portuguese and Italian Translations of the book Python For Everybody by Dr. Charles Russell Severance

* Update free-programming-books.md

Updated the link to the latest edition.

* Update free-programming-books.md

Updated edition for the book with author and links in three places.

* Update free-programming-books.md

Added Think DSP - Digital Signal Processing in Python.

* Update free-programming-books.md

Added Think Data Structures: Algorithms and Information Retrieval in Java.

* Update free-programming-books.md

Added two new books;
Think C++: How To Think Like a Computer Scientist
Modeling and Simulation in Python

* Minor changes to adhere to Contributing.md

Thanks to @kashirash
Suggested edits to pass travis-ci and respecting markdown formatting.