Fix org#2579 About incorrect JSON generated from empty Messages resource

Fix org#2579 About incorrect JSON generated from empty Messages resource

The broken JSON from bdirjson output is caused by defining in Messages
resource message types with negation but without using 'All' keyword
at the beginning of the message type list. It is:

 Append = /var/log/bacula/bacula.log = !Debug, !Saved, !Skipped
 Console = !Debug, !Saved, !Skipped

instead of

 Append = /var/log/bacula/bacula.log = All, !Debug, !Saved, !Skipped
 Console = All, !Debug, !Saved, !Skipped