Refactored the configuration layer, and expose a 'configure' command

is it a good idea to drop the support of the Symfony LTS ? This would give you 2 choices:

- continue maintaining a separate version for people using the LTS (either in full-featured mode, which would be really weird according to semver, or in bugfix-only mode, which will make them complain)
- stop bothering about the LTS version, which is a very bad message for the community, especially coming from a package maintained by SensioLabs