sync remote files to tftpdir

before remote kernel and initrd were not synced to tftp dir (see removed
comment) which lead to unusable pxe configs because in pxe config a not
synced kernel/initrd was referenced (e.g.
append initrd=/images/sles-11-sp3-x86_64_test/initrd.gz)
Merge pull request #977 from mvdlinde/tftp_sync_remote

sync remote files to tftpdir