Fix useractionsmenu

Always set tiling_floating.
Add first attempt at config ui
Set correct metadata.desktop for config
Add bladelayout
Hook up bladelayout
Enable configuration through UI.

This needs a couple of workarounds:

- Qt won't convert a QStringList to an Array, instead giving an utterly
  useless QVariant(QStringList) (without any methods and presumably only
  containing the pointer)

- The config group _needs_ to be empty, else it's not accessible from
  the javascript side