overrides: Add kernel patch for BFQ scheduler.

This contains a small sed "patch" for supporting kernel 3.15, but will
be dropped as soon as the new BFQ patches will be released for 3.15.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Enable BFQ scheduler on all machines by default.

This adds the kernel patch to all machines and uses it as the default
scheduler. Let's see when I need to scream at the edit of a commit
message again, because the disk is busy and the editor is waiting for
I/O.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>