-q should use default values where nothing is specified

[henning]

I believe that all config options should have a default, and in fact, in the interactive run, they have.

As such, when running on the command line with -q, I expect the installer to use defaults where I don't specify anything explicitly.

I think that's the most convenient way for everybody to deal with.

Like this people can write scripts to fully automate a new project setup with minimum effort, as they only need to specify non default values, at the same time everybody wanting to specify anything can still do so.