Update entity_provider.rst

Fixed Fatal Error for UsernameNotFoundException
Merge pull request #279 from lucabartoli/patch-3

Update entity_provider.rst
Negation problem in event_listener.rst
Merge pull request #308 from antoinediligent/patch-1

Negation problem in event_listener.rst
Merging #309
Merging #310
Mise à jour de la commande d'installation des vendors avec composer
Merge pull request #311 from nicolas-bastien/patch-1

Mise à jour de la commande d'installation des vendors avec composer
Merging #314 + typo fix
Adding missing references + merging #315
Merging #318
Merging #321
Merging #316
Merging #317
Fix link in routing.rst
Merging #323
Merging #324
Merging #325
Merging #326
Merging #328