Introduce config options to define session/cache handling in USM module.

See https://bugs.open-xchange.com/show_bug.cgi?id=23041#c33

com.openexchange.usm.cache.session.timeout=43200

Specifies a timeout (in seconds) after which USM sessions that are not accessed will be removed from memory. Removed sessions will be automatically restored from DB on next access, but since server changes couldn't be traced while the session was not in memory, the client has to perform an (incremental) sync for each folder (it will be notified that each folder changed regardless of any real server changes). Default: 43200s = 12h


com.openexchange.usm.cache.syncstate.timeout=3600

Specifies a timeout (in seconds) after which cached SyncStates that are not accessed will be removed from memory. Removed SyncStates will be automatically restored from DB on next access. Default: 3600s = 1h