function getStoredCredentials(log, callback) {
    metadata.getObjectMD(managementDatabaseName, tokenConfigurationKey, {},
        log, callback);
}
Retrieves Orbit API token from the management database.

The token is used to authenticate stat posting and

@param  {werelogs~Logger} log Request-scoped logger to be able to trace
 initialization process
@param  {function} callback Function called with (error, result)

@returns {undefined}