Checkbox GUI (Legacy) 0.34

  * checkbox-gui: Add all the methods to export results to json format
    Fixes https://bugs.launchpad.net/checkbox-gui/+bug/1452217
  * checkbox-gui: Replace SDK Dialog by DarkDialog element
  * checkbox-gui: Fix WideDialog to get a Dark background (same as in
    SDK 14.04) Both the Style and the FocusScope are merged into a
    single component making it non stylable by the Theme and
    guarantying the Dark backgroung for all versions of the Ubuntu
    SDK.
  * checkbox-gui: Add the DarkDialog qml component In order to still
    get the dark background popup that we used to gave with the first
    version of the Ubuntu SDK, the DarkDialog component now provides
    the Dialog popups for checkbox-gui. Overriding StyledItem is not
    possible so the Main Container is an UbuntuShape instead of a
    FocusScope based element.
  * checkbox-gui: Use the new exporter units This patch first adds the
    exporter units to the unit_list used to create a legacy session in
    highlevel.py. The dbus service, gui-engine, RunManagerView.qml and
    SubmissionDialog.qml all have methods to export results. They all
    now get a new parameter to pass the exporter unit name got from
    QSettings.