`sudo` required to run demos

[miccio-dk]

As per title, sudo is required by the demo scripts and it's not installed by default on the container.
This can be easily fixed with apt-get update && apt-get -y install sudo.

[dtrawins]

our direction is to drop the dependency on the sudo in the container. Demos should not require it. In new images from the coming releases, it should be improved.
The container could be executed in any security context so using sudo wouldn't be convenient and secure. If there are any operation in the container which requires privileged access, it is better to start the container with --user root parameter.