If a script or archive is specified with an absolute path
in the image description, kiwi should not assume this path
to exist below the image description directory but just take
the absolute path as it is. Fixes#70
At the moment there is no class to build the pxe client config
file from information provided with the optional pxedeploy
section. However this is not fatal to the build because the file
could be created manually too. Thus a warning message is shown
which will go away when the pxe client config file creation
has been ported
