users can now write blog posts for the group page
Merge branch 'master' of https://github.com/softwerkskammer/Agora

Conflicts:
	lib/groups/views/get.jade
added suggestions from andreas:
 - handles bad cases for blog data like empty files, missing dates, missing bodies
 - now uses async.map
- blog internationalisiert
- moved getBlogPosts to WikiAPI
Merge pull request #519 from holger-s/master

users can now write blog posts for the group page