Document update message with a big history can cause problem with maximum header size

Right now, each document update also sends a list with the version numbers and date of previous versions to help produce a more accurate conflict resolution.

The problem is that this does not play well with the maximum header size of various application servers (8K in Jetty and Tomcat) when the document has a huge history.

The best would probably be to introduce a configurable maximum duration or number of versions (but harder to configure).