Complete zeroing
Complete zeroing

This patch will do all that is necessary to allow the helper VM to do
whatever it will do with the zeroing image in place - which is,
hopefully, to zero out the disks of the instance.

Signed-off-by: Hrvoje Ribicic <be5828fca31f89218048bec4189e30a581aa65da@google.com>
Reviewed-by: Jose A. Lopes <0fb9c4f8511df4ec2ae28af879e9d462f6218a2c@google.com>

andir/ganeti,onponomarev/ganeti,apyrgio/ganeti,bitemyapp/ganeti,leshchevds/ganeti,ganeti/ganeti,leshchevds/ganeti,andir/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,onponomarev/ganeti,ganeti/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,yiannist/ganeti,mbakke/ganeti,mbakke/ganeti,dimara/ganeti,mbakke/ganeti,yiannist/ganeti,leshchevds/ganeti,yiannist/ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1,dimara/ganeti,ganeti/ganeti,apyrgio/ganeti