Bug 19946: (follow-up) Add fixed footer to authorities Z39.50 popup

Bug 19946: (follow-up) Add fixed footer to authorities Z39.50 popup

This patch adds additional Bootstrap framework markup to the search form
so that the "Save" and "Cancel" controls are in a fixed footer at the
bottom of the window. This prevents the controls from disappearing down
off screen.

This patch also adds some whitespace to the "Author
(meeting/conference)" label to enable better word wrapping.

To test, apply the patch and go to Authorities -> New from Z39.50/SRU.
In the popup window, both the search form and search results pages
should look correct.

Patch applies, form resizes, displays and functions as expected.
Signed-off-by: Dilan Johnpullé <dilan@calyx.net.au>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>