Bug 17336: Add api_secret_passphrase entry in packages setup

Bug 17336: Add api_secret_passphrase entry in packages setup

Bug 13799 introduced the api_secret_passphrase on source installs, but missed to do so on packages.

This patch introduces the entry on the template koha-conf-site.xml.in file, and
patches koha-create so it generates a randomized string (64 chars) to put in it.

To test:
- Apply the patch
- Grab the new template file:
  $ sudo cp kohaclone/debian/templates/koha-conf-site.xml.in \
            /etc/koha
- Create a new instance:
  $ kohaclone/debian/scripts/koha-create --create-db blah
=> SUCCESS: The script runs fine, /etc/koha/sites/blah/koha-conf.xml
   contains the api_secret_passphrase entry.
- Sign off :-D

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>