Merge pull request #512 from symfony-fr/2.4

Merging 2.4
Update monolog.rst

Fix typo
Correction d'une coquille (otion => option)
Update form_collections.rst
update

updated according to changes and simplification of FlorianKoerner

Simplified "Ensuring the database persistence" example
https://github.com/symfony/symfony-docs/commit/f4306ac502d28bd1ee9bbc1b321f550f1f85429f
Merge pull request #520 from symfony-fr/2.4

Merging 2.4
Merge pull request #515 from nclavaud/patch-1

Fix typo in monolog.rst
Merge pull request #517 from netgusto/patch-1

Correction d'une coquille (otion => option)
Merge pull request #519 from florida63/master

Update form_collections.rst
Merging #516