ping remote host before backup +minor changes

- test ping with remote host before backup
- replace $RUN_FCT_SSH with $RUN_CMD_SSH whereever it is possible
backupData.sh: fct ensureRemoteFSExists updated

fct ensureRemoteFSExists, so that it does not use the global variable
$I_DEST_POOL any more, but uses the fs provided as parameter of the
function only
backupData.sh: comments improved in header
backupData.sh: fixes #8