Mount data disk on Rackspace

This checks for the presence of `/dev/xvde1` which is where Rackspace mounts larger data disks on their performance line of hardware types. This takes that disk and mounts it into `/data` so that it is usable.
think we need an ``|| true`` or similar at the end.  if the box doesn't have /dev/xvde1, ssh_exec will return 1 and fail the task