Add optional push to S3 and handle group permissions better

Add a new optional flag for pushing to S3 using s3cmd

Handle group permissions on dirs / files better.  If you have a monitoring system you need the monitoring system to be able to read the dir to check timestamps.  Adding a _BACKUP_GROUP that the user can set to the group of their monitoring app solves this.

Also I fixed the restore mechanism.  It was totally broken due to -P vs. -p in tar