Add file upload resource

#56

![postman-3](https://cloud.githubusercontent.com/assets/125707/3352672/5d168a64-fa54-11e3-9d0f-172489852b02.jpg)

I think it would be better to have an authorizer manager (for the request level access, not the entity level) that it's instantiated from a restful-level generic menu access callback. That would simplify testing for user access to hook_menu generated items.

Something like:
```php
function hook_menu() {
  $items['…'] = array(
    …
    'access callback' => 'restful_menu_access_authorization',
    …
  );
  $items['…']['access arguments'] = $items['…']['page arguments'] + array('custom option1', 'custom option2');
  return $items;
}

…

function restful_menu_access_authorization($plugin_type, $version) {
  $additional_args = array_slice(2, func_get_args());
  $authorizerManager = \RestfulBase::authorizerManager($plugin_type, $version, $additional_args);
  return $authorizerManager->authorize();
}
```