content: Fix imported posts (markdown syntax, article types)

The auto-importer has created several issues with the markdown syntax which
needed manual fixing. Additionally quite a lot of event annoucements were
categorized as article.

content/blog/2016/2016-08-22-35yc3-35-jahre-ccc/index.md

@@ -1,7 +1,7 @@
 ---
 authors:
 - hansenerd
-categories: article
+categories: event
 draft: false
 lastmod: '2016-08-22T11:33:08+02:00'
 publishDate: '2016-08-22T11:33:08+02:00'
@@ -15,4 +15,3 @@ Euch feiern!
 
 Finden tut ihr uns in der Viktoria-Kaserene, zugang über den Hof der
  Bodenstedtstraße 16 oder über den Eingang im Zeiseweg 9
-