Feature/smart routing syntax

This is an introduction of a new rad routing syntax. We have discuss it with @docteurklein. So, in order to activate this new routing syntax just turn off the older one in the `config.yml` :

```yaml
knp_rad:
    routing_loader:
        old: false
```

By default the older system is activated. So no compatibility break.

This is a short sample of the new syntax : 

```yaml
# default routing support
default_syntax:
   pattern: '/default'

# complete rad routing. Generate :
# some_rad_resource_index  [GET]        /tests
# some_rad_resource_new    [GET]        /tests/new
# some_rad_resource_create [POST]       /tests
# some_rad_resource_show   [GET]        /tests/{Test_id}
# some_rad_resource_edit   [GET]        /tests/{Test_id}/edit
# some_rad_resource_update [PUT|PATCH]  /tests/{Test_id}
# some_rad_resource_delete [DELETE]     /tests/{Test_id}
@some_rad_resource:
    resource: App:Test
    property: 'id'
    actions: ~

# some shotcuts
@App:Test: ~

# parent resource support. Generate :
# app_child_index   [GET]       /tests/{Test_id}/children
# app_child_new     [GET]       /tests/{Test_id}/children/new
# app_child_create  [POST]      /tests/{Test_id}/children
# app_child_show    [GET]       /tests/{Test_id}/children/{Child_slug}
# app_child_update  [PUT|PATCH] /tests/{Test_id}/children/{Child_slug}
# app_child_delete  [DELETE]    /tests/{Test_id}/children/{Child_slug}
@App:Child:
    parent: some_rad_resource
    property: 'slug'
    actions: ~

# defined custom actions. Generate :
# app_foo_custom [GET] /custom
# app_foo_index  [GET] /foos
@App:Foo:
    actions:
        custom:
            pattern: '/custom'
            methods: GET
        index: ~
```