mate-polkit should provide policykit-1-gnome

[Martin Wimpress]

Hi,

I've just pushed a simple commit to `mate-polkit`.

During a Ubuntu MATE Remix install the `software-center` is installed
which results in `gnome-session` being pulled in because
`software-center` depends on `policykit-1-gnome` or `policykit-1-kde`.
As shown below.

    aptitude why gnome-session

    i   software-center Depends    policykit-1-gnome | policykit-1-kde
    p   lxsession       Provides   policykit-1-gnome
    p   lxsession       Recommends openbox | x-window-manager
    p   mutter          Provides   x-window-manager
    p   mutter          Recommends gnome-session | x-session-manager

I modified `mate-polkit`, the MATE authentication agent for PolicyKit-1,
to Provide `policykit-1-gnome` just as `lxsession` has done to work
around this issue.

-- 
Regards, Martin.