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
Added C++ online site, learncpp.com
first list of spanish resources
Add more books to the german list. Also ordered the list alphabetically.
Try to fix markdown.
Merge pull request #178 from mgaitan/lista_español

first list of spanish resources
Try to fix markdown again.
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
I really hate this markdown thing...
Finally kiss my markdown...
Add more books and fixed markdown
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