Merge pull request #1102 from nlegoff/last_locale

[3.8.4] Last locale version
Allow to search unknown document type through API
Merge pull request #1103 from nlegoff/allow_unknown_type

[3.8.4] Allow to search unknown media type
Fix empty of collection
Fix inscription
Merge pull request #1104 from nlegoff/fix-bugs

[3.8.4] Fix some bugs
Add extended response format for API
Add content negociation provider
Add content negotiation event subscriber
Accept default header
Fix tests