The feature notes:

  * Mitaka is now the default OpenStack release configured by this
    profile.  Kilo and Juno are deprecated, and we are no longer testing
    the profile's functionality under those versions (although we have
    no concrete plans to remove the code at this point).  They may
    continue to work, or they may not.  You should update to Mitaka if
    possible, of course.

  * The default topology is now down to two nodes: a controller (`ctl`)
    node and a compute (`cp-1`) node; the networkmanager node's
    functionality has been moved to the controller, as is the default in
    the OpenStack Ubuntu/Apt documentation.  You can return to the old
    three-node configuration by changing the name of the
    "networkmanager" node in the Advanced Parameters from `ctl` to `nm`.

  * One of the bigger Mitaka features is shared filesystem support
    (Manila).  We download a shared filesystem image and configure
    Manila so that you can immediately create a share and connect it to
    guests.

  * We have added support for the Neutron ML2 "Linuxbridge" driver,
    although we continue to install the "OpenVSwitch" ML2 driver by
    default.  The Linuxbridge driver is not as well-tested as the
    OpenVSwitch driver, in all possible configurations of this profile.
    Although OpenStack has switched to the linuxbridge driver as its
    default, we have no plans to do that yet.

  * You can now choose an Apt mirror and set a custom mirror path if you
    require fast localized access to a mirror.

  * The MTU that dnsmasq pushes to your OpenStack VMs has been reduced
    from 1454 bytes to 1450 bytes.  1454 is an adequate setting for GRE
    tunnels, of course, but not for VXLAN networks, which require 1450
    on a normal physical network with 1500-byte MTU.  Somehow this
    mistake escaped prior testing.

A few details:

  * I refactored the Neutron ML2 plugin setup code, since all nodes
    have to be configured essentially the same way.  Moreover, it
    supports either openvswitch or linuxbridge.

  * I haven't setup Manila for aarch64 because there is no available
    Manila service image for aarch64.  Have to build one of my own.