Bug 32633: (QA follow-up) Add handling for authorities merge

Bug 32633: (QA follow-up) Add handling for authorities merge

When you first click 'actions -> merge' from a result in the authories
search page you will see a new 'Merging with authority: ' text appear at
the top of the search results.

Prior to this patch, the text appears outside of the white page-section
and is almost un-noticable.

After this patch, we add a page-section with bg-info (blue backround)
around the merge message which makes it stand up more clearly.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit c2664482e4d82c0a728301dfb57476909c3f609c)
Signed-off-by: Jacob O'Mara <jacob.omara@ptfs-europe.com>