fsa_lv_backup.py: metadata_backup(), sysdisk => metadata, and get 'df -h' info;
  backup_one_lv(), must now specify LVs in 'cfg.lvs_to_backup'
  backup_one_partition(), check for a valid Linux partition-path
config_edit.py:  sysdisk => metadata; created a 'if cfg.debug' debugging-section