Add configurations for kdbus demo

Add two new configuration files to build systems for QEMU/{x86,ARM} to
showcase kdbus.
Merge qt5wayland demo.
webkiosk: new package

This new package provides webkiosk, a sample program that display web
pages using QtWebkit.
configs: add config for webkiosk demo on rpi.

Add a configuration file to build a kernel and rootfs to showcase
webkiosk on Raspberry Pi.