Add support for html entities

Decode html entities in post content to support french special characters (some themes store html entity in post table). See Issue : https://github.com/Yoast/wordpress-seo/issues/613
Add support for html entities

Change to respect php coding standards
Change javascript code to decode also html entities
Formatting

Replace spaces by tabs
Merge pull request #632 from julienmeyer/master

Add support for html entities