This function is called from the supervisor at system start-up.
Inserts all data in the configuration files into the database and destroys all old rows with StorageType volatile. The rows created from the configuration file will have StorageType nonVolatile.
All snmp counters are set to zero.
If an error is found in the configuration file, it is reported using the function config_err/2 of the error report module, and the function fails with the reason configuration_error.
ConfDir is a string which points to the directory where the configuration files are found.
The configuration file read is: usm.conf.