Change backup filenames

appbackup_%s_%s-v%s.tar.gz -> app_%s_%s_v%s.tar.gz
    drop 'backup'. rationale: it is known these files are backups
    timestamp has '-'. rationale: colon in filename confuses tools like scp (they think it is a hostname)

backup_%s-v%s.tar.gz -> box_%s_v%s.tar.gz
    drop 'backup' and name it 'box'. this makes it clear it related to the box backup
    timestamp has '-'. rationale: colon in filename confuses tools like scp (they think it is a hostname)

Part of #159

src/scripts/backupapp.sh

@@ -50,7 +50,7 @@ elif [[ "$1" == "filesystem" ]]; then
 fi
 
 # perform backup
-readonly now=$(date "+%Y-%m-%dT%H:%M:%S")
+readonly now=$(date "+%Y-%m-%d-%H%M%S")
 readonly app_data_dir="${DATA_DIR}/${app_id}"
 readonly app_data_snapshot="${DATA_DIR}/snapshots/${app_id}-${now}"