Bug 20658: Move template JavaScript to the footer: Installer and onboarding

Bug 20658: Move template JavaScript to the footer: Installer and onboarding

This patch updates the installer and onboarding templates so that
JavaScript is included in the footer instead of the header. A new
include file is added, installer-intranet-bottom.inc, so that only
required JS is being loaded.

Some markup changes are included to improve validity.

To test, apply the patch and start with a blank Koha database. Run
through the installer and onboarding processes and confirm that there
are no problems. Check especially JS-related interactions like
datepickers and fields which are validated via JS, like the password
inputs.

NOTE: The qa tool will flag this patch for not using the Asset plugin,
but it doesn't work correctly for installer files.

Signed-off-by: Claire Gravely <claire.gravely@bsz-bw.de>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 9ceb745fb2f9c226ffab40a32137c8d43d10ad74)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>