Modified all Dockerfile to add lounge user and set permissions on the…

[Need-To-Learn]

… /home/needtolearn/data folder

Hi,
I think it's a good practice to not run app as root user.
So I modified the three Dockerfile to add an user 'lounge' and set right permissions on the $HOME/data folder.

[williamboman]

The container actually ran as non-root user before, but we dropped it (in #17) because of volume permission hassle. I'd definitely prefer not to run it as root but due to the amount of people with varying Docker experience that use the official images I'd rather run as root than deal with support (maybe proper documentation will help mitigate that).

I wouldn't say I have very detailed knowledge about the security implications of running containers in privileged mode, my conception is that the only reason not to run as root is if you believe there are flaws (or hedge against potential flaws) in LXC and/or Docker-specific virtualization/containerization implementation. Please reopen this if you strongly disagree!