[WIP] Aenv 257 & API endoint for AENV-280

- [x] - AENV-257 - Locked articles can be loaded
- [x] - AENV-280 - As a user I want to close and unlock an article
i don't like that ;/ 

We should lock resources with POST (/articles/{number}/{language}/lock/) - this should lock article
Unlocking should be done with DELETE (/articles/{number}/{language}/lock/) - this should unlock article