make 'activate' use the new connections, fixes undefined errors

This removes the "old" way of activating a disk in favor of using the new connection objects that makes all these calls so much easy to read and give much better output.

Example output:

    ceph-deploy osd activate node1:/tmp/osd0
    [ceph_deploy.osd][DEBUG ] Activating cluster ceph disks node1:/tmp/osd0:
    [ceph_deploy.sudo_pushy][DEBUG ] will use a remote connection with sudo
    [ceph_deploy.osd][INFO  ] Distro info: Ubuntu 12.04 precise
    [ceph_deploy.osd][DEBUG ] activating host node1 disk /tmp/osd0
    [ceph_deploy.osd][DEBUG ] will use init type: upstart
    [node1][INFO  ] Running command: ceph-disk-activate --mark-init upstart --mount /tmp/osd0
    [node1][INFO  ] got latest monmap
    [node1][INFO  ] added key for osd.0
    [node1][ERROR ] 2013-09-30 15:23:41.777013 7f78c06b1780 -1 journal FileJournal::_open: disabling aio for non-block journal.  Use journal_force_aio to force use of aio anyway
    [node1][ERROR ] 2013-09-30 15:23:41.795342 7f78c06b1780 -1 filestore(/tmp/osd0) limited size xattrs -- filestore_xattr_use_omap enabled
    [node1][ERROR ] 2013-09-30 15:23:41.811948 7f78c06b1780 -1 journal FileJournal::_open: disabling aio for non-block journal.  Use journal_force_aio to force use of aio anyway
    [node1][ERROR ] 2013-09-30 15:23:41.812533 7f78c06b1780 -1 filestore(/tmp/osd0) could not find 23c2fcde/osd_superblock/0//-1 in index: (2) No such file or directory
    [node1][ERROR ] 2013-09-30 15:23:41.857576 7f78c06b1780 -1 created object store /tmp/osd0 journal /tmp/osd0/journal for osd.0 fsid cfcd3a44-9fa0-4160-8d6a-0367be0e6c06
    [node1][ERROR ] 2013-09-30 15:23:41.857644 7f78c06b1780 -1 auth: error reading file: /tmp/osd0/keyring: can't open /tmp/osd0/keyring: (2) No such file or directory
    [node1][ERROR ] 2013-09-30 15:23:41.857717 7f78c06b1780 -1 created new key in keyring /tmp/osd0/keyring
    [node1][ERROR ] 2013-09-30 15:23:41.873500 7fd13a145780 -1 read 56 bytes from /tmp/osd0/keyring