storage: if LVM volume groups are available, allow an SR to be created on one

This uses the ezlvm script-based storage adapter. Note the storage will
use raw block devices and blkback -- no blkback dependency.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Start the xapi-storage-script service (needed by ezlvm)

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Always sync the database before triggering a host reboot.

Failing to do this can undo all the network and SR configuration.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Tell the user to re-run the wizard after the reboot

Some actions need to be performed after the reboot. It's always safe to
re-run the wizard to check.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Debian/Ubuntu: don't fail if 'chkconfig' doesn't exist

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Merge pull request #74 from djs55/lvm

Offer to set up an ezlvm SR on existing LVM