Bug 26905: Purchase suggestion button hidden for users with suggestion permission...

Bug 26905: Purchase suggestion button hidden for users with suggestion permission but not acq permission

This patch adds a link to purchase suggestions from the header menu's
"More" submenu for users with suggestions management permission.

To test, apply the patch and log in to the staff interface as a user
with "suggestions_manage" permission.

- Click the "More" menu item in the header. You should see a link to
  "Suggestions" which takes you to the suggestions management page.

- Log in as a user without "suggestions_manage" permission. The link
  should not appear.

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>