Merge pull request #763 from esparta/master

[es] Added a Python book
Cleaned French line
French Link
markdown formatting to make url parsing easier

BAD : (http://www.jsoftware.com/books/pdf/calculus.pdf)(PDF)
GOOD: (http://www.jsoftware.com/books/pdf/calculus.pdf) (PDF)

BAD : ([PDF](http://www.kamishima.net/archive/mlmpyja.pdf), [EPUB](http://www.kamishima.net/archive/mlmpyja.epub))- 神嶌敏弘
GOOD: [PDF](http://www.kamishima.net/archive/mlmpyja.pdf), [EPUB](http://www.kamishima.net/archive/mlmpyja.epub) - 神嶌敏弘

BAD : (http://introcs.cs.princeton.edu/java/home/)- Robert
GOOD: (http://introcs.cs.princeton.edu/java/home/) - Robert
good/bad examples of adding book entries
Merge pull request #764 from borgified/url_fixes_easier_parsing

markdown formatting to make url parsing easier
Merge pull request #765 from borgified/update_contributing_format

good/bad examples of adding book entries
[en] Adding Perl Book (and removing Perl 6 duplicated)