[Xend/ACM] Automatic loading of policy after xend has started.

[Xend/ACM] Automatic loading of policy after xend has started.

On systems where the grub bootloader is not available or active the
to-be-activated policy is written a simple textfile. Once xend has
started the contents can be read. Using 'xm setpolicy' the policy can
be activated and the Domain-0 label set (using 'xm addlabel').
I fixed some bugs in the grub bootloader handler on the way and
removed some dead functions.

Signed-off-by: Stefan Berger <stefanb@us.ibm.com>