config: Migrate to the new version. Remove backend details.

Migrate to new config format v4.
```
{
	"version": "4",
	"credential": {
		"accessKey": "WLGDGYAQYIGI833EV05A",
		"secretKey": "BYvgJM101sHngl2uzjXS/OBF/aMxAN06JrJ3qJlF"
	},
	"region": "us-east-1",
	"logger": {
		"console": {
			"enable": true,
			"level": "fatal"
		},
		"file": {
			"enable": false,
			"fileName": "",
			"level": "error"
		},
		"syslog": {
			"enable": false,
			"address": "",
			"level": "debug"
		}
	}
}
```

This patch also updates [minio cli spec](./minio.md)

docker/start.sh

@@ -1,14 +1,10 @@
 #!/bin/bash
 
-if [ "$1" = 'fs' ]; then
-    if [ -z "$2" ]; then
-        echo "Invalid arguments"
-        echo "Usage: fs <export_dir>"
-        exit 1
-    else
-        /bin/mkdir -p "$2" && /minio init fs "$2" && /minio server
-    fi
+## Fix this check when we arrive at XL.
+if [ -z "$1" ]; then
+    echo "Invalid arguments"
+    echo "Usage: <export_dir>"
+    exit 1
 else
-    echo "Usage: fs <export_dir>"
-    exit 0
+    /bin/mkdir -p "$2" && /minio server "$2"
 fi