added code to lock you out of the tool if the tool has been updated and there is database changes that need to be applied
changed handling of devices to use /dev/xvd instead of /dev/sd, resolves #5 by explicitly setting the xen virtual device so that it does not get remapped by the OS
added code to back support systems that were previously using /dev/sd
added database script to rewrite the block_device values to the new style