Bug 16239 [CSS Follow-up] Upgrade Bootstrap in the staff client

Bug 16239 [CSS Follow-up] Upgrade Bootstrap in the staff client

This followup tweaks some CSS and markup in order to correct conflicts
between default Bootstrap styles and the expected (previous) style of
the staff client. Included:

- Corrections to the widths of some modals.
- Corrections to the style of the <pre> tag, seen often in MARC preview
  modals.
- Corrections to the default active and hover states for dropdown menus.

To test, apply the patch and view various pages which use Bootstrap
modals, confirming that they look correct.

- Add order from staged file MARC preview
- Add order from external source MARC preview
- Cataloging record merge MARC preview
- Batch record modification MARC preview
- Authorities Z39.50 search MARC preview

Signed-off-by: Claire Gravely <claire_gravely@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>