Switch back to orbit stack by default
    
    The dbus stack apparently isn't working too well:
    
    http://lists.fedoraproject.org/pipermail/desktop/2010-October/006568.html
    
        Regarding orca not reading the contents of windows, etc (what leads to
        orca only announcing key presses) I have a sort of solution.
    
        Before saying what I needed to do, this fix will make orca still use
        at-spi over corba. I know that the intention was to have fedora 14 use
        at-spi over dbus but as time is running out, I have been unable to find
        a solution using at-spi over dbus and there shouldn't be any difference
        to the user at the moment (if anything at-spi-corba is more likely to be
        reliable as at-spi-dbus is in early days), it may be worth considering
        this so we at least have a working orca.
    
    This commit just changes the default value in the gconf schema.