Implement filesystem layer

Add to config:
knp_gaufrette:
adapters:
local:
local:
directory: %kernel.root_dir%/../web/uploads/documents
filesystems:
integrated:
adapter: local

integrated_storage:
resolver:
integrated:
public: /uploads/documents

Add to composer.json:
"integrated/storage-bundle": "~0.4",

Add to AppKernel.php:
new Knp\Bundle\GaufretteBundle\KnpGaufretteBundle(),
new Integrated\Bundle\StorageBundle\IntegratedStorageBundle(),