add javascript garden
Add some ruby books and courses

* Code Academy Ruby
* How to think like a computer scientist: Learning with ruby
* Ruby in twenty minutes
* Ruby Essentials
* Ruby Learning
Update free-programming-books.md

added javascript's http://devdocs.io/
Merge pull request #175 from tk120404/patch-1

Update free-programming-books.md
Merge pull request #176 from crushmaster/master

Add german book list (more will follow soon)
Added C++ online site, learncpp.com
first list of spanish resources
Merge pull request #178 from mgaitan/lista_español

first list of spanish resources
Merge pull request #177 from xexio/master

Added C++ online site, learncpp.com
Merge pull request #154 from vicmaster/add_ruby_books_and_courses

Add some ruby books and courses
Merge pull request #179 from crushmaster/master

Add more books to the list and fixed markdown
Added the HoTT book.
Merge pull request #180 from Xazax-hun/master

Added the HoTT book.
Added book to Machine Learning section

Textbook draft of Probabilistic Models in the Study of Language.
Update free-programming-books.md

I added some more Free Python sources and a link to PDF file.
Add a link to Mother Tongues of Computer Languages

Great poster!
Add Mother Tongues of Computer Languages Poster
added git section
Added Think Like (a) Git to the Git book list.
Added "wie werde ich unix guru"