Add page type blog

[mbruellmann]

On http://swiss.github.io/styleguide/design_principles_-_basic_grid_and_page_types.html add a new page type "Blog". The page consists of

• header
• date, comments, topcis, keywords, author, quick feedback (stars/likes)
• lead
• text
• visuals
• comment-funcition
• comments

Example:

[bit-pro-iew-eui]

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