Some improvements

* Added contributors list to `composer.json` (linked to github contributors graph)
* Improved Behat context
* Fixed/Cleaned/Tested configure options handling
* add `--default` option to `install` command
@stof I'm aware of the `--no-interaction` but I think `--defaults` is more user-friendly in this case.
Also, what if we want to ask other question ? For example, when the build fails, we ask the user if he wants to see the log. With no-interaction we could not do that properly.