Update free-programming-books-gr.md
Added HTML/CSS and Swift courses
Updated link
Added english book about reverse engineering
Merge pull request #1120 from grogy/reverse-engineering

Added english book about reverse engineering
Two podcasts added to the list of javascript
Merge pull request #1121 from gabrielalmir10/patch-3

Two podcasts added to the list of javascript
Changed link

Mathematics for Computer Science (November 2013 Version) old link directed to a page that requested password, used a new link that doesn't require one.
Merge pull request #1124 from JIGD/master

Changed link
Added Raspberry Pi User Guide

This User Guide is written by Eben Upton, Co-Creator of the Raspberry Pi
Merge pull request #1126 from kumaresa18/master

Added Raspberry Pi User Guide
Added 'Erlang in Anger'
Merge pull request #1127 from miku/erlang-in-anger

Erlang in Anger
推荐一本nodojs的书  

a book about nodejs
Merge pull request #1129 from 0532/patch-2

推荐一本nodojs的书
fixed a dead link in zh.md
Merge pull request #1130 from sunxb10/master

fixed a dead link in zh.md
Update free-programming-books-fr.md

error HTTP 403.
Merge pull request #1131 from Creaprog/patch-1

Update free-programming-books-fr.md
29000