Log Message:
Added sql to create additional database indices supporting deletion. Without
these indices web browser will often timeout before delete operation completes.

Update to libpreludedb 0.9.8. Changes:
- Always use prelude_escape_binary() when inserting additional data, even in case
  we're inserting a string, since the database field might be of a type that require
  binary kind of escaping. Fix #143.
- Implement reading of message_processing_model, security_model, security_level.
  Handling of community member is deprecated (IDMEFv16 update).
- Fix a bug where Service->ip_version would not be read from database.
- Error reporting improvement.