server: Startup sequence should be more idempotent. (#2974)

Fixes #2971 - honors ignore-disks option properly.
Fixes #2969 - change the net.Dial to have a timeout of 3secs.

cmd/object-common.go

@@ -194,7 +194,7 @@ func xlHouseKeeping(storageDisks []StorageAPI) error {
 			err := cleanupDir(disk, minioMetaBucket, tmpMetaPrefix)
 			if err != nil {
 				switch errorCause(err) {
-				case errDiskNotFound, errVolumeNotFound:
+				case errDiskNotFound, errVolumeNotFound, errFileNotFound:
 				default:
 					errs[index] = err
 				}