Vl conf refactor

[atrakeur]

Refactored framework configuration management.

• Moved Configuration to his own component
• Configuration is now binded to his own ServiceProvider
• Removed all calls to Configuration inside the Application component
• Configuration now load config.json and config.env.json where env is the environement the framework is running on (dev, prod, staging, whatever)

Also, configuration now use nconf package (see https://github.com/indexzero/nconf ) to avoid maintaining low level code ourself.

Loading from files allow the config to be gitignored easily (avoid credentials in code versionning). Also loading different files depending on the environnement allow the config to be switched easily.