Support Pinterest recipe pins

[jwnichls]

Requires marking up our recipes with the h-recipe microformat or the Schema.org recipe tags. This would require a better wiki format for entering recipes and probably the parsing of recipes into a structured format.

https://help.pinterest.com/entries/23762433-Add-rich-pins-to-your-site

http://microformats.org/wiki/hrecipe
http://schema.org/Recipe