lava-docker is insecure

[akbennett]

The root password is "password"
The lava superuser is "admin" with password "admin"
There is a APIkey that is stored in the root of the docker image that is the same on other docker images.

[fboudra]

We shouldn't use the root user, but create maybe a lava user. We don't want to set a password but use an ssh key that can be mount as a volume by the user. I can send such example if you want to go this road (Linaro CI docker images doesn't contain credentials and it's the approach I use today)

[fboudra]

Here's the example: #12