Fix for issue #3887: Dynamic assured replication configuration change may give few timeouts

When doing a modrate on as DS where assured replication is not enabled, 
if you enable assured replication (safe-data or safe-read) with dsconfig 
at the same time, you may get some timeouts for some messages at the 
beginning. This is due to the fact that new configuration values are set 
(assured boolean set to true) before reconnection occurs. So messages 
are fired in assured mode and then just after, the connection is broken 
to reconnect with new configuration to the topology. This may make the 
messages fired before reconnection fail in timeout.

Fix: read new conf, disconnect, store new conf, reconnect