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
@pierrejoye ``--no-interaction`` will disable all interaction (at least all interaction done through the dedicated Symfony APIs, which should hopefully be used in all places).

@jubianchi dispalying the logs would actually be a good candidate for something based on the output verbosity rather than an interaction