Bug 10240: (follow-up) disable logout/set library

Bug 10240: (follow-up) disable logout/set library

Logging out/setting the library does not work while using offline
mode, so it makes no sense to present those options to the user.
Much better is some sort of explanatory message informing them that
those two links don't work.

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>