Overhaul (#4)

**README**
- Overhaul; changed docs to be better aligned to the new `backup.sh`.
- Add example `docker-compose`.

**Dockerfile**
- Install `zip`.
- Remove installation of `sqlite`.
- Remove unnecessary variables.

**backup.sh**
- Overhaul; now zips all required and recommended files and directories stated at [vaultwarden docs](https://github.com/dani-garcia/vaultwarden/wiki/Backing-up-your-vault).
- Removed deleting old backups; will be added later on in a separate script.

**entrypoint.sh**
- Removed creating folders.

entrypoint.sh

@@ -1,41 +1,10 @@
 #!/bin/sh
-# vim: tabstop=2 shiftwidth=2 expandtab
-
-#set -x
 
 BACKUP_CMD="/sbin/su-exec ${UID}:${GID} /app/backup.sh"
 
 echo "Running $(basename "$0") as $(id)"
 
-# Preparation
-BACKUP_DIR=$(dirname "$BACKUP_FILE")
-if [ ! -d "$BACKUP_DIR" ]
-then
-  echo "$BACKUP_DIR not exists. Creating it with owner $UID:$GID and permissions $BACKUP_FILE_PERMISSIONS."
-  install -o $UID -g $GID -m $BACKUP_FILE_PERMISSIONS -d $BACKUP_DIR
-fi
-
-ATTACHMENT_BACKUP_DIR=$(dirname "$ATTACHMENT_BACKUP_FILE")
-if [ ! -d "$ATTACHMENT_BACKUP_DIR" ]
-then
-   echo "$ATTACHMENT_BACKUP_DIR not exists. Creating it with owner $UID:$GID and permissions $BACKUP_FILE_PERMISSIONS."
-   install -o $UID -g $GID -m $BACKUP_FILE_PERMISSIONS -d $ATTACHMENT_BACKUP_DIR 
-fi
-
-SEND_BACKUP_DIR=$(dirname "$SEND_BACKUP_FILE")
-if [ ! -d "$SEND_BACKUP_DIR" ]
-then
-   echo "$SEND_BACKUP_DIR not exists. Creating it with owner $UID:$GID and permissions $BACKUP_FILE_PERMISSIONS."
-   install -o $UID -g $GID -m $BACKUP_FILE_PERMISSIONS -d $SEND_BACKUP_DIR 
-fi
-
-# For compatibility reasons
-if [ "$1" = "/backup.sh" ]; then
-  >&2 echo "Using /backup.sh is deprecated and will be removed in future versions! Please use \`manual\` as argument instead"
-  $BACKUP_CMD
-fi
-
-# Just run the backup script
+# Run backup script once ($1 = First argument passed).
 if [ "$1" = "manual" ]; then
   $BACKUP_CMD
   exit 0
@@ -46,7 +15,6 @@ if [ "$(id -u)" -eq 0 ] && [ "$(grep -c "$BACKUP_CMD" "$CRONFILE")" -eq 0 ]; the
   echo "Initalizing..."
   echo "Writing backup command \"$BACKUP_CMD\" to cron."
   echo "$CRON_TIME $BACKUP_CMD >> $LOGFILE 2>&1" | crontab -
-
 fi
 
 # Start crond if it's not running