Add a LogEntry csv writer

We want to export audit as CSV files.

For that we need to add CSV writers to write LogEntry as CSV in order to query them through available REST endpoint.

We want to control what the writer will write. We could use fetch.property mechanism to do that. We will write properties given by the fetch if provided otherwise write default ones (id, eventId, category, date, username, document, comment).

Extended infos won't be written by this writer for now due to its complexity.