SSDM-1388 handle backup of remote databases. Improve error messaging.

installation/resource/installer/bin/backup-databases.sh

installation/resource/installer/bin/chmodx-all-scripts.sh

installation/resource/installer/bin/common-functions.sh

...lation/resource/installer/bin/database-existence-check.sh

installation/resource/installer/bin/finish-installation.sh

...cisd/openbis/installer/izpack/AbstractScriptExecutor.java

...sx/cisd/openbis/installer/izpack/ExecuteBackupAction.java

...d/openbis/installer/izpack/ExecuteSetupScriptsAction.java

.../openbis/installer/izpack/SetDatabasesToBackupAction.java