[WIP] Internal refactoring

The goal of this PR is to implement translatable resource repository which can work irrespective of admin bundle. It is necessary for example in doctrine data fixtures or any other CLI scripts. 

This PR requires some changes in Admin Bundle:

`FSi\Bundle\AdminBundle\Doctrine\Admin\Context\Resource\Context.php`:
`$element` should be `protected`
`$form` should be `protected`
`function createFormData(array $resources)` should be `protected`
`function buildForm(FormBuilderInterface $builder, array $resources)` should be `protected`

Except of that, any other fsi-open bundle remains untouched.


Work in progress, any comments are welcome.