[dbapi] Connection.load_appobjects should load site_cubicweb files as well, they may contains necessary RQL extension function definitions. Also kill some broken deprecated code in this method.
option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')