Bug 27777: (alternate) Improve tables on Point of Sale page for low screen resolutions

Bug 27777: (alternate) Improve tables on Point of Sale page for low screen resolutions

This alternate solution makes these minor changes:

- The Bootstrap grid classes are adjusted so that the breakpoint
  between the two-column layout and the single-column layout happens at
  a wider browser-width.
- The DataTable configurations are modified to set "autoWidth" to
  "false," which gives us a more fluid behavior.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>