Restricted Drivers Manager is visible in the menu for non-admin user

Trivial fix, thanks for spotting this.

 restricted-manager (0.15) feisty; urgency=low
 .
   * debian/control: Use XS-Python-Version 'all' instead of 'current', since
     the latter seems to break quite often on upgrades. (see #93795)
   * applications/restricted-manager.desktop.in: Do not show for non-admins.
     (LP: #97163)
   * Add RestrictedManager/xorgconfig.py (stolen from kdeguidance):
     Parser/writer for X.org configuration files. Add author and copyright to
     debian/copyright.
   * RestrictedManager/xorgconfig.py: Change formatting a bit to make it more
     similar to what dexconf produces.
   * RestrictedManager/xorg_driver.py:
     - Use xorgconfig.py to mangle /etc/X11/xorg.conf directly instead of
       relying on consistent debconf values and using dexconf. This makes r-m
       work with custom configurations (including install scripts from
       nvidia/fglrx upstream packages) and avoids changing unrelated settings
       like keyboard/screen resolution/BusID etc. (LP: #92836, LP: #94549,
       LP: #93075)
     - Back up the entire original config before enabling a driver. If it
       exists when disabling again, restore it entirely. (LP: #96474)
     - is_enabled(): Do not check for installed GLX library package any more
       (such as nvidia-glx), since they could be installed directly from
       upstream. Now only check the xorg.conf configuration. (LP: #94626)
     - Add {enable,disable}_config_hook() for nonstandard modifications to the
       X.org configuration.
   * RestrictedManager/fglrx.py: Use above *_config_hook() to add/remove the
     'Extensions' section and disable Composite. In previous versions, dexconf
     did that for us.
   * restricted-manager: Drop check for readability of debconf database, since
     we do not need it any more.
   * Some small UI improvements, thanks to izi!
     - Remove the redundant 'Enable' button, we already have the check boxes.
     - Display stock yes/no/reload icons in addition to the textual status.
     - Add window icon.
     - Do not update the tree model when cancelling enabling/disabling.
     - Make modal dialogs transient.
   * RestrictedManager/core.py: Add a global variable
     package_install_idle_function which, if set to a function, is executed
     repeatedly while waiting for synaptic to finish. This avoids GTK specific
     code in the backend.
   * restricted-manager: Set core.package_install_idle_function to a default
     GTK event processing loop. (LP: #97399)
   * restricted-manager: Determine main window xid and pass it to synaptic as
     parent window, so that it becomes transient.