fix: install script

added dynamic backup folder (fixed #79)
changed if statements

Cron/autoBackup.sh

@@ -1,6 +1,7 @@
 # cron-timing: 05 01  *   *   1
 container_name="arbeitszeitmessung-main-db-1"
 filename=backup-$(date '+%d%m%Y').sql
+backup_folder=__BACKUP_FOLDER__
 database_name=__DATABASE__
-docker exec $container_name pg_dump $database_name > /home/pi/arbeitszeitmessung-backup/$filename
+docker exec $container_name pg_dump $database_name > $backup_folder/$filename
 echo "created backup file: "$filename