Bug 17391: Add missing prefs to sysprefs.sql

Bug 17391: Add missing prefs to sysprefs.sql

Adds
- ReturnpathDefault
- ReplytoDefault
to the sysprefs.sql file.

To test:
- Run the web installer in any language
- Check all preferences are installed without error
- Check prefs listed above now exsit in your
  systempreferences table

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>