Bug 36640: (follow-up) CSS fixes for DataTables controls

Bug 36640: (follow-up) CSS fixes for DataTables controls

This patch adds CSS fixes to try to keep styling of DataTables and
related controls consistent with how it looked before the upgrade.

This version of DataTables introduced a lot of usage of "!important" in
the CSS which severly limited our options. For that reason I modified
the file to remove all of those instances. Both the minified and
unminified versions are changed.

This patch continues the pre-upgrade practice of picking only the
relevant DataTables CSS and including it in our CSS build. This means a
smaller total CSS download for the user and eliminates the "!important"
problem.

Signed-off-by: Jake Deery <jake.deery@ptfs-europe.com>
Signed-off-by: Lisette Scheer <lisette@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>