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/2014/2014-07-03-cryptoparty-sprechstunde/index.md

@@ -1,7 +1,7 @@
 ---
 authors:
 - hansenerd
-categories: article
+categories: event
 draft: false
 lastmod: '2014-07-03T17:16:36+02:00'
 publishDate: '2014-07-03T17:16:36+02:00'
@@ -15,4 +15,3 @@ zwischen 19 und 21 Uhr in unseren Vereinsräumen vorbei.
  Der erste Termin ist schon heute!
 
 [Wegbeschreibung](//www.hamburg.ccc.de/wegbeschreibung)
-