add support for persistent storage

[dexter21767-dev]

now beamup-sync-and-deploy creates a fixed size virtual disk image and mount it to the docker container.

the draw back is that the disk image will be created with that fixed size regardless of if the container actually uses it or not.

TODO:

• make the volumes auto mount on startup
• use ansible to create create these files

/etc/auto.indirect                                                                   
*       -fstype=ext4    :/home/beamup/docker_volumes/&_data

/etc/auto.master
/mnt/beamup     /etc/auto.indirect     --timeout=180

note: the volume is mounted to /persistent_data inside the container