Bug 27471: Change auth merge success link text and don't redirect

Bug 27471: Change auth merge success link text and don't redirect

Test Plan:
1. Follow the steps above to reproduce
2. Notice how there is no message telling the user that the merge was
successsful
3. Apply patch
4. Repeat step 1
5. Now notice how the user is redirected to a page with a message that
says that the merge was successful, and there is a link with helpful
text to view the merged record

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>