Throw an exception when a shared service has a circular reference

With Pimple, it's easy to create services with a circular reference. This PR adds an exception to break before the infinite loop.

Unfortunately, it's not possible to get the name of the service.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

Symfony DI throws a similar exception : 
https://github.com/symfony/symfony/blob/master/src/Symfony/Component/DependencyInjection/ContainerBuilder.php#L475