Merge pull request #294 from etomlef/master

added Learn to Program by Chris Pine (under Ruby)
Update free-programming-books-pt_BR.md

Introducao ao Shell Script - Aurelio ( Verde ) 
Tutorial de Ruby - Eustaquio Rangel
Merge pull request #295 from ataliba/ruby-shell

Update free-programming-books-pt_BR.md
updating readme
Merge pull request #296 from johand/update_readme

updating readme
Update free-programming-books-pt_BR.md

Python para desenvolvedores
Merge pull request #297 from ataliba/python-pt-BR

Update free-programming-books-pt_BR.md
Added Git Immersion Spanish, Immersion en Python 3 and Doma de Serpientes para Niños
Merge pull request #298 from esparta/master

3 more spanish books (mostly translations from english books)
add Backbone.js API Link
Some spanish books about javacript and css
Add item(free-programming-books-ko.md)
Added COBOL section with 2 PDFs
Fixed COBOL case
Markdown links need to be lowercase

[COBOL] (#cobol)  works but [COBOL] (#COBOL) doesn't
Merge pull request #299 from minsOne/master

add Backbone.js API Link, README Item
Merge pull request #300 from rodacato/master

Some spanish books about javacript and css
Merge pull request #301 from JoePlant/master

Added COBOL section with 2 PDFs
Lisp pdf link
Merge pull request #302 from OpenCode/patch-4

Lisp pdf link