Composer and directory structure

Composer with discussed packages.
Directory structure:
- `features` - for behat scenarios
- `src` - for app logic
- `var` - for compiled templates and cache
- `web` - public directory
I think we should aim for largest group available - even if its means that we still support 5.3.
But not further - 5.3 brought lot of important stuff, that changed way of writing PHP code and its organisation.

Moss framework and storage work on 5.3 to 5.6 - so decission is up to @marcotroisi