RFE: sysprep file name should be according to its version

We are using sysprep inside a floppy by the filename: sysprep.inf, -
which is what sysprep is looking for in .ini file format that was in xp
and 2003.
The new format is xml and the filename should be "Unattend.xml" for this
versions.

Change-Id: Ie1aff3a70c4d34c3e4ba74152e61551f09d33fff
Bug-Url: https://bugzilla.redhat.com/1145999
Signed-off-by: Shahar Havivi <shaharh@redhat.com>