Liquid tag system for displaying archives by year

Lifted from
http://mikerowecode.com/2010/08/jekyll_archives_grouped_by_year.html
Use 'Posts' instead of 'Blog'

Makes it more clear the link leads to a list of posts
Merge branch 'feature/yearly-archives'
Merge branch 'fix/posts-names'
NP: Comprehensive hiatus
Merge branch 'draft/comprehensive-hiatus'