Bug 19983: Switch single-column templates to Bootstrap grid: Authorities

Bug 19983: Switch single-column templates to Bootstrap grid: Authorities

This patch updates several single-column Authorities module templates to
use the Bootstrap grid.

- authorities-home - The home page of the Authorities module.
- authorities.tt - The authority add/edit page.
- blinddetail-biblio-search.tt - Not really testable -- It's the small
  popup window which appears during the process of linking an authority
  to a MARC record.
- detail.tt - The authority detail page. Search for an authority record
  and click on the "details" link in the search results.
- merge.tt - From a list of authority search results, select "Merge"
  from the Actions menu of two authority records. Test both the initial
  selection screen and the source/destination merging view.
- searchresultlist.tt - The authority search results page.

Each of these pages should look correct, with a single centered column
with wide margins on either side. At lower browser widths the margins
should disappear.

Signed-off-by: Claire Gravely <claire.gravely@bsz-bw.de>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>