ubuntu sdk references obsolete system-image channel names: 'devel', 'devel-proposed', 'rtm-14.09', [...]

After attempting to drop some channel redirects from system-image.ubuntu.com that were put in place for upgrade compatibility over a year ago, and which we believed were now obsolete, I received a report that this was causing the SDK to fail at provisioning from channels.

Looking at the source, I can confirm that the ubuntu-sdk references the deprecated channel names (deprecated because they are unqualified).

share/qtcreator/ubuntu/qml/DevicesPage/NewEmulatorDialog.qml, lines 41ff:

        model: ["devel",
                "devel-proposed",
                "stable",
                "rtm-14.09",
                "rtm-14.09-proposed",
                "custom channel"]
    }

I have temporarily restored the 'devel' and 'devel-proposed' redirects, but these channels should be mapped as follows:

  devel -> ubuntu-touch/devel/ubuntu
  devel-proposed -> ubuntu-touch/devel-proposed/ubuntu
  stable -> ubuntu-touch/stable/bq-aquaris.en
  rtm-14.09 -> ubuntu-touch/rc/bq-aquaris.en
  rtm-14.09-proposed -> ubuntu-touch/rc-proposed/ubuntu

(Sorry for the inconsistency in where the channels are pointing - the problem is, we haven't promoted any images on some of these channels using the community custom tarball, only the BQ one! We will eventually correct this, but for the moment the above is the correct mapping based on where those channels actually redirect.)

There are also examples given in ./share/qtcreator/ubuntu/scripts/device_flashdaily and ./share/qtcreator/ubuntu/scripts/device_flashdaily_bootstrap that need to be corrected.