Refacto services

This is a quite big change in how container is build.

- container now is able to build without a config file (useful for using services in command like `init`)
- services handing files/resources have be re-built (I'm still not 100% satisfied with it but it'll do the job for now).
- push & pull commands now handle options defined in the config file (fix #22, except for the global options)
- init command has been simplified

For the init command, let me know what you think @b-durand:

- the 7 options have been replaced by 2 optionnals arguments: the url and the project slug. For example, with the following command, you will only be asked about files (it's way simpler to copy/paste a single url than specify many separated options). Missing information are still asked

```
# Every params about server & project could be defined
openl10n init https://user:userpass@openl10n.dev/ foobar

# Here you will be ask about user + password + project slug
openl10n init https://openl10n.dev
```

- if a configuration file is already present in the folder, then it will read it first (and if it is complete, no question will be asked). It's useful when you already create the file but have not create the project on the server.
 
je rajoute un `"php": ">=5.4",` dans `composer.json` du coup ? :D