salt.module.mdadm: a few sanity checks
salt.module.mdadm: a few sanity checks

    - Test for mdadm in __virtual__()
    - Make sure the device ie: /dev/md0 exists before running mdadm
      on it. It is easier to blow up before executing a command

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt