Allow to preconfigure bugtraq plugin settings in /.tgitconfig

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Initialize variable

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Fixed issue #1726: Rebasing issues with empty commits

Signed-off-by: Sven Strickroth <email@cs-ware.de>