Update free-programming-books.md

Adding RESTful Web Services book
Update free-programming-books.md

Moved HtDP and SICP from "free-programming-books-en.md"
Fix codecademy zh locale
FreeBSD initial @mzs114 #534
PC-BSD Init @mzs114 #534
Merge pull request #532 from Semyonic/patch-1

Update Scheme #532
Merge pull request #188 from manoj-agarwal/patch-1

Adding RESTful Web Services book
Web Services Indexing
move some non x86 to the non-x86 section
added several books

added more free Chinese programming books in:
* git
* ruby
* LISP
* Haskell
* Scala
* Shell script
Merge pull request #537 from ailurus1991/patch-1

added several books
Merge pull request #536 from linkslice/master

move some non x86 to the non-x86 section
Quick fix to zh list
Merge pull request #538 from jgpacker/patch-1

Quick fix to zh list
Added postgresql section.
Merge pull request #539 from Kindrat/master

Added postgresql section.
Fixed link in table of contents to .NET section
Merge pull request #540 from kohenkatz/patch-1

Fixed link in table of contents to .NET section
Update free-programming-books.md
Remove duplicate entry

The removed line corresponds with the Haskell Wikibook link which is already present. (The wikibook link is usually more updated than the removed pdf version. Also you can download pdf version of this book from the wikibook link.)