Stop logging out critical info of database

The signer will print out the user name and password of the database
which could cause security problem.

The server side is OK.

Signed-off-by: Hu Keping <hukeping@huawei.com>

cmd/notary-signer/main.go

@@ -104,7 +104,6 @@ func setUpCryptoservices(configuration *viper.Viper, allowedBackends []string) (
 		if err != nil {
 			return nil, fmt.Errorf("failed to create a new keydbstore: %v", err)
 		}
-		logrus.Debugf("Using %s DB: %s", storeConfig.Backend, storeConfig.Source)
 
 		health.RegisterPeriodicFunc(
 			"DB operational", dbStore.HealthCheck, time.Second*60)