Bug 26290: Add option forsetting default SMTP parameters in koha-conf.xml

Bug 26290: Add option forsetting default SMTP parameters in koha-conf.xml

This patch adds an entry to koha-conf.xml for setting a default SMTP
server config. 'koha-create' gets option switches for all options.

To test:
1. Use the tweaked script to crete a new instance
2. Notice it contains entries for smtp_server and they respect your
   options.
3. If you don't choose any option, it sets the current default.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>