a number of improvements for install_demo.sh

[dirkpetersen]

1. [x] not clear where install_demo.sh is in the github repos, cannot send pull requests to improve it

2. [x] warnings in the script that pip is outdated, always install latest pip first with pip3 install --upgrade pip

3. [x] script should always install latest docker-compose because it is easy:

   COMPOSE_VERSION=$(curl -s https://api.github.com/repos/docker/compose/releases/latest | grep 'tag_name' | cut -d\" -f4)
   sudo curl -L "https://github.com/docker/compose/releases/download/${COMPOSE_VERSION}/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose && chmod +x /usr/local/bin/docker-compose

4. [x] - at the end script should tell user what to do next (e.g. now go to http://blabla ), currently it only says

   Creating network "db4sci_default" with the default driver
   Creating dbaas ... done
   Creating mydb-web ... done

5. [x] - people are not supposed to install the distro version of docker so we need to tell them where the right location is if the wrong version of docker is installed, e.g. https://docs.docker.com/install/linux/docker-ce/ubuntu/

[dirkpetersen]

fixed