Merge pull request #13 from fcrozat/master

enable installation images for SLED [FATE#316328]
Merge pull request #14 from fcrozat/master

 ensure prepare_image is called [FATE#316328]
add whole autoyast to first stage
Merge pull request #15 from yast/add_whole_autoyast

add whole autoyast to first stage
GNOME SLE Classic is known as "sle-classic" now