Demo shell scripts should bail after first command fails

[andyk]

Currently, documentation/demos/demo_ilya_papag_from_cli.sh will keep on running subsequent commands after a given command fails. This probably doesn't make sense, and instead the script should stop running after any command in it fails (i.e. returns non-zero exit status).

This can be done by changing set -x at the top of the script to set -xe.