*   Update problem-sets-competitive-programming.md

 Added LeetCode platform  in Competitive Programming section.

* Update problem-sets-competitive-programming.md

Added LeetCode platform in  Competitive Programming

Remove R interactive tutorial from the list as it redirects to Pluralsight instead of CodeSchool

* Update link to "Advanced Linux Programming"

* Mark book as PDF

* Fix authors names

* Update link to "Advanced Linux Programming"

* Mark book as PDF

* Add Italian C/C++ resources

* Update free-programming-books-it.md

Fix TravisCI error

* Update free-courses-en.md

Google's machine learning crash course added

* Update free-courses-en.md

Alphabetic order changed

* Remove broken links in Italian books

* Add Italian Perl resources

* Add year of pubblication of the Perl course

* Update free programming books it

* UPDATE free-programming-books in italian

* Added year of pubblication of the js course

* Update year of pubblication in italian

* Added author to js course

* Removed trailing slash from URL

* Update README

* Update Readme with CC BY licence

* DRY: link to LICENSE.md, not to CC. also spelling

* Update free-courses-it adding a Javascript course

* Update free-courses-it.md

* Move some courses to free-courses-pl.md

* Fix for Travis CI

* Add C, C++ and C# courses

* Move some courses to free-courses-pl.md

* Fix for Travis CI

* Add Italian database free books

* Add Italian MySQL guide

* Add many books and courses

* Fix for travis.ci

* add assembly book, clojure doc + cleanup

* I'm guessing the linter treats '-' as a space

* Add Italian Database resources

* Update free-programming-books-it.md

Fix Travis error

* Add C# courses

* Add C# book