Recalculate statistics when server configuration is changed as a result of a command
While reviewing !197 we found a general issue that statistics needs to be recalculated when incremental changes are applied to the configuration. The specific case discussed in !197 was that when new subnet is added to the database and the server detects this change, it will fetch the subnet data and merge the subnet into the configuration it is currently running. Because, it bypasses the staging/commit phase, the statistics is not recalculated.
We also checked that subnet_cmds doesn't deal with this problem either. We may need to find some generic solution for it.