Bug 22197: Add Mana KB link to administration sidebar menu

Bug 22197: Add Mana KB link to administration sidebar menu

This patch adds a link to the Mana KB configuration page to the
administration sidebar menu.

To test, apply the patch and:

 - Log in to the staff client as a user who lacks permission to manage
   Mana KB.
   - Go to an Administration page which shows the sidebar, like
     Libraries or Patron categories. There should be no link to Mana KB
     in the left-hand sidebar.
 - Log in to the staff client as a user who has permission to manage
   Mana KB.
   - Go to Administration -> Mana KB
     - In the sidebar menu you should see a link to Mana KB and it
       should be bold.
   - Navigate to another Administration page which shows the sidebar.
     The Mana KB link should not be highlighted.

Signed-off-by: Maryse Simard <maryse.simard@inlibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>