added cmd 'lw' for creating the first admin user also from the comman…

[ingobaab]

I am currently building an installer-script for lxd-dashboard and want to create the initial admin from the shell script. For that I need the possibility to create the initial admin user from the command line. I need also to create the client.crt and client.key files to automate my install.sh script. Maybe the script will be extended to also use getopt later...