openSUSE Security Update : rmt-server (openSUSE-2019-1824)

This update for rmt-server to version 2.3.1 fixes the following issues : - Fix mirroring logic when errors are encountered bsc1140492 - Refactor RMT::Mirror to download metadata/licenses in parallel - Check repo metadata GPG signatures during mirroring bsc1132690 - Add rmt-server-config subpackag...