Implement the ceph osd destroy feature in ceph-deploy.

    Feature:
        1. handle osd already out
        2. handle osd did not blong any hostname
        3. handle osd is not in acting set

    Usage: ceph-deploy osd destroy <hostname> --osd-id <osd_id>

    I have tested in CentOS6/7, Ubuntu12.04/14.04 and it work normally.
    This feature can help to remove osd quickly. It maybe is helpful for
    newbie who uses ceph.

    If you have any questions, feel free to let me know.
    Thanks!

    Signed-off-by: Vicente Cheng <freeze.bilsted@gmail.com>