Bug 15752: (QA follow-up) Inform user that patron was automatically switched

Bug 15752: (QA follow-up) Inform user that patron was automatically switched

Test plan:

1) Start checking out to some patron - there should be no message about
auto switching
2) read the another patrons card - note the patron is switched and there
is a message about it at top of the main page content

Followed test plan, patch worked as described. Passed QA test tool
Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>