Enable nanoc deploy to gh-pages branch

Author: rbuch

config.yaml

@@ -76,3 +76,8 @@ watcher:
   # When to send notifications (using Growl or notify-send).
   notify_on_compilation_success: true
   notify_on_compilation_failure: true
+
+deploy:
+  default:
+    kind: git
+    branch: gh-pages