Investigate lock issues and handle lock expiration

• Do we really need to lock the document when putting a WOPI lock?
• When 2 users are editing a document through Office Online, how can they update both the document as the document is locked by the first user?
• WOPI locks should last 30 minutes, how should we handle that on Nuxeo? If the document keeps being locked, Office Online won't be able to edit it until someone unlocks it.

WOPI locks last 30 minutes => uses the KeyValue store without any TTL. Add a scheduler that will check if the locks are expired and so unlock the related document.