First steps for an own wiki.

* Scaffold for Page Objekt
* Using textile for rendering html
* Easy wiki-links with [[wikipage]]

app/views/layouts/_main_tabnav.html.erb

@@ -16,6 +16,11 @@
           { :name => "Aufgaben", :url => "/tasks"}
         ]
       },
+      { :name => "Wiki", :url => "/pages", :active => ["pages", "wiki"],
+        :subnav => [
+          { :name => "Alle Seiten", :url => "pages/all" }
+        ]
+      },
       { :name => "Bestellungen", :url => u.ordergroup ? "/ordering/" : "/orders",
         :active => ["orders", "ordering"],
         :subnav => [