Bug 9008: warn if user is logged-in with admin account
Test plan:
* log-in staff interface with admin (mysql) account => there's a large warning on the homepage
* log-in with another account => nothing displayed
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com> Passed-QA-by: Jonathan Druart <jonathan.druart@biblibre.com> Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com> Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>