Move housekeeping before object layer initialization (#3001)

In a distributed setup that the server should not perform any operation
on the storage layer after it is exported via RPC. e.g, cleaning up of
temporary directories under .minio.sys/tmp may interfere with ongoing
PUT objects being served by the distributed setup.

cmd/server-main.go

@@ -313,6 +313,9 @@ func serverMain(c *cli.Context) {
 	// Check 'server' cli arguments.
 	storageDisks := validateDisks(disks, ignoredDisks)
 
+	// Cleanup objects that weren't successfully written into the namespace.
+	fatalIf(houseKeeping(storageDisks), "Unable to purge temporary files.")
+
 	// If https.
 	tls := isSSL()