qt4e: add 2 images

qt4e: add 2 images

- qt4e-base-image : contains qt4 embedded libraries and can be used
as a base rootfs when developping using the sdk
- qt4e-demo-image : contains qt-base-image + qt-demo + a script to
launch qt-demo at boot, this image can be used to quickly setup
a demonstration of qt capabilities on a machine using qtdemo
- qt-demo-init : recipe creating the package which provides the
init script to lauch qtdemo.

Signed-off-by: Eric Bénard <eric@eukrea.com>
Acked-by: Khem Raj <raj.khem@gmail.com>