Added formatter and PHP engine support....

Moved money and currency formatting into a dedicated "formatter" class
Added templating helpers for PHP engine
Added templating/engines nodes into Configuration nodes
Moved twig extensions into Twig\Extension namespaces for respecting Symfony bundles coding standards
Added phpunit and dbunit to composer dev dependencies
Updated tests and added real twig tests

This also allows (and that's why I did the PR in the first place) to use money formatter anywhere (i.e: when formatting data in a datagrid, but in the controller).